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The 75-79 Nova shares axle and mounting dimensions with the 70-81 Camaro and F-bird, 68-74 Nova shares with 67-69 Camaro. I've done the same swap you are thinking of--79 Trans Am rear into 76 nova, no problems at all.
12-bolt truck would be a poor choice, as you would need to move perches and get aftermarket axles, and they have a smaller diameter pinion shaft.

Any advantages to keeping sbc springs in the front with a bbc in the car? Pros and cons to those that have tried it each way?
FRONT SPRINGS....SBC....Your ride height will be lower for that low rider stance that is currently popular (pro). Your suspension travel will be limited by that low rider stance that is currently popular (con). You save money on springs (pro). It will cost you money in shock and tire wear (con). Ride will be harsher as spring rate of stock springs are progressive and the soft part is gone (pro or con depending upon how you like your car to ride). You will win every burn out contest because all of the weight is over the nose of the car (pro). You will not obtain as much weight transfer if you should ever decide to participate in a contest of acceleration (con).

SUSPENSION coil springs, 1934-2007, standard, custom made. Coil Spring Specialties LLC, PO Box G, 632 W Bertrand, St Mary's, KS 66536, 785-437-2025 or coilsprings.com

Frame mounts.

BB FRAME BRACKETS
Here are measurements of BB Frame brackets from "phel69" a Team Camaro forum member.
"These are the heights of a set of big block brackets in a car I have.

1. Driver's side is 2.5 inches from base to the top of the bracket. It measures 1.75 inches from base to center of the bracket bolt hole. It is GM part # 3950113.

2. The passenger side bracket measures 2.0 inches from the base to the top of the bracket. It measures 1&3/8 inches from the base to the center of the bracket bolt hole.This is GM part # 3950114.

They are different for a BB. Then just get the engine mounts for a 69 or 70 nova with BB. The frame mounts are what your engine mounts will bolt to in the frame. On your radiator support look at how it is cut out on the passenger side, then look at the driver side and you will see where to make the cut.
The BB crossmember is different too. The BB frame stands move the engine to the pass side a little. I have read that you can oblong the holes on a SB one to work. The Z bar is also longer on the BB.
The BB crossmember is different too. The BB frame stands move the engine to the pass side a little. I have read that you can oblong the holes on a SB one to work. The Z bar is also longer on the BB.
I know of a guy (friend of friend) who did a bb swap that had almost the same list of problems. It turned out in that he had installed the bb frame mounts incorrectly. He had the left on the right and the right on the left. From what I understand they can be bolted up on the wrong side??? He lifted the motor and swapped the mounts and then had no problems. Short one is on the passenger side.
You will need to get the BB frame mounts so the engine sits in there right.
The taller frame mount goes on the driver side (left). Just did this swap on a 68 and encountered no problems.
The SB frame mounts will make a BB sit high, and also will not offset the motor to the passenger side as the factory did (to clear the big Saginaw power steering box)
You really need the frame stands and mounts, header fitment becomes impossible otherwise.

The B.B. mounts make the engine sit lower and over to the right(pass side)...Headers wont clear the streeing box with the S.B mounts.
Big-blocks also got a different trans crossmember, so the trans mount is also located a little to the right, to match the motor mounting. '67-'69 Camaros use the same subframe as your car, so you can use a Camaro crossmember.
If you plan to use the T-350 with a BBC, you'll need to use a big-block manual-transmission crossmember. Big-block cars never got a T-350 from the factory, only a T-400, but the T-350 will mount to the same holes that a stick-shift does. Look at the bottom of your current crossmember and notice that the cutout where you find the trans mount bolts is oval-shaped. On the BBC crossmember, that cutout is more squared-off. You might be able to modify yours to work, if you can't find the BBC unit.
Buy hooker regular competition headers for the swap.These headers offer the best fit.Many smaller tube headers are a more universal design that fit multiple chassis,but dont fit any one chassis all that well.The hooker headers cost a bit more,but of you ever had to change the starter or oil filter,you will appriciate how correct they fit.Good luck.

ENGINES:
All '70-'72 454 motors (LS5 and LS6) came with a forged crankshaft. The LS5 had 2-bolt mains and the LS6 had 4-bolt mains.
The 325 HP 396 (L35), and the '70-'72 402 (LS3) came with a cast crank and 2-bolt mains. The 350 HP 396 (L34) came with a forged crank, and is usually a 4-bolt block, but may possibly come as a 2-bolt block also. All 375 HP 396's (L78 and L89) came with forged cranks and 4-bolt mains.

GEAR RATIOS - TRANSMISSIONS:
Just remember, you don't need a steeper gear if you have an OD tranny, you can actually run a lower rear end gear than you would with a 3 speed auto. The 1st and 2nd gear of an OD tranny are much steeper than a 3 speed. So you can run a much lower rear end than you ever could in a 3 speed, and still have the same launch as a 3 speed with a steep gear all the while benefiting from the OD by having great highway driving also.

Basically, you put a 3.08 gear in a 3 speed, you will have lackluster launches and OK highway driving. You put that same 3.08 rear end in a car with a 4speed auto, and you will have great launches and SUPERB highway driving. For first and second gear, and 3.08 rear end with a 4 speed auto will feel like 1st and 2nd gear of a 3.73 rear end in a 3 speed auto.

Its all because of these "final drive" ratios that you will see at the axle:

__3speed auto with 3.73_____ 4 speed auto with 3.08
1st gear___ 9.40______________________9.42
2nd gear___5.67______________________5.02
3rd gear ___3.73______________________ 3.08
4th gear ___NA _______________________2.16

Final drive ratio is the multiplication of the trannys gear and the rear end. The first gear ratio of a 350 trans is 2.52. Multiply 2.52 x 3.73 and you get 9.40 as a final drive ratio at the axle in first gear. The first gear of a 700r4 is 3.06. Multiply 3.06 x 3.08 and you get 9.42, which is darn near identical to the final drive ratio of a 350 trans with a 3.73 (9.40 vs 9.42)

What that means is that your 4 speed auto with a 3.08 rear will perform just like a 3 speed auto with a 3.73 in first gear because the first gear final drive ratio numbers are almost identical. In second gear, the 4 speed auto with 3.08 will feel real close to a 3 speed auto with a 3.73. And 3rd gear in the 4 speed gives you a straight up 3.08 rear, and in OD, its just like being in 3rd gear with a 4 speed with a rear end gear of 2.16!!! Major MPG!!!

BUT, Rex, your 3.73 rear end with an 2004r trans in 4th gear would work out to be like having a 2.50 rear end. Still great highway MPG and low RPMS. 1st and second gear would be similar to a 4.10 with a 350 tranny. REAL quick off the line.

I'm not trying to tell anyone what to do, I'm just trying to help by explaining what I've learned recently. I used to think that the 4 speed autos would let you run a steeper rear end gear and not kill you on the highway. But in reality, with a 4 speed auto you don't need to run a steeper rear end gear for racing because the 4 speed auto already has steeper gears inside of it for you for 1st and 2nd. That allows a lower rear end gear to be installed, and really helps out on the long hauls.

More on transmissions here

AIR CONDITIONING:
The 375 horsepower 396 and the 450 horsepower 454 could NOT be ordered with air conditioning. The main reason was that the air conditioning compressors were not suited to the high-rpm nature of the solid-lifter engines. A secondary reason was that the demands of air conditioning on these solid-lifter motors could cause them to overheat if left idling too long with the air conditioning on.

Chevy Production Big Blocks:
The Chevy big block was introduced in 1965 with a 396 cid Mark IV engine developed from the 1963 Datona mystery engine. The engine was basically developed as an answer to the highly successful GTO with its 389 cid engine introduced in 1964. The 396 was first offered in the Chevelle at 375 HP, in the full size Chevy as 325 and 425 HP versions and in the Corvette with up to 425 HP. In 1966 the 396 was bored out to 4.250" producing a 427 cid engine. The 427 was offered in the 1967 Impala SS rated at 385 HP and in the Corvette it was first offered in 1966 and was uprated with 3-2 bbl carburetors to 435 HP for 1967.

In 1967 the L88 427 was also provided in approximately 20 Corvettes with an advertised HP of 430 but actually producing in excess of 550 HP. The L88 required minimum 95 octane gas to avoid possible damage to the engine and was meant to be strictly for racing. 1970 saw introduction of a stroked 427 resulting in a 454 cid engine. The 454 was offered in the 1970 Impala, Chevelle SS, El Camino SS and Monte Carlo SS in a 360 HP version and in the Chevelle and El Camino SS in a 450 HP version. The 1970 Corvette LS-6 was offered with the 390 HP 454 cid engine. 1970 also ushered in the 402 cid engine which was also known as the 396 in some Chevys and the big block 400 in others. In the 1970 Camaro SS, Chevelle SS and Nova SS the 402 cid engine with 375 HP was known as the 396 and the cars carried the 396 badge. From 1970 to 1972 the 402, 454, 465 and 495 cid engines were introduced.

The short big block V8 has a deck height (centerline of crankshaft to cylinder deck measured along the centerline of the bore) of 9.80" and a height (centerline of crankshaft to top of engine along the center of the V) of 10.75". Cylinders are spaced on 4.84" centers on each bank and the centers of cylinders on the two banks are offset to accommodate the two connecting rods on each crank journal. The big blocks have been produced in 3.935", 4.096", 4.125", 4.250", and 4.440" bores and strokes of 3.47", 3.76", and 4.00". Over the years from 1965 to 1995 the big blocks were offered in nine different displacements from 366 cid to 502 cid.

Chevy made big-block crankshafts in two different strokes. The 396, 402, and the 427 all use a stroke of 3.76 inches. These are internally balanced crankshafts. The 454 uses a 4-inch stroke and is externally balanced. All the main-bearing journal diameters for the Mark IV big-blocks are 2.7482 to 2.7492 inches, with the rear main-journal diameter at 2.7478 to 2.7488 inches. The rod bearing?s journal diameters measure 2.1988 to 2.1998 inches, making the crankshafts interchangeable.

There are two different types of big-block crankshafts, cast or forged. You can tell the difference by the parting line on the crankshaft throws. The cast crankshafts will have a thin parting line where the two halves were joined to make the complete crankshaft, while the forged crankshaft will have a wider parting line. The 427 Corvette crankshafts are all forged steel.

Heads:
open chambers have bigger combustion chambers (118 to 123 cc) and tend to flow better due to unshrouded valves and slightly larger oval ports.

closed chambers have smaller chambers (100 to 112cc)

Closed chambers were needed to get the compression up on the smaller 396, 402, and 427 engines. A 454 can build compression with open chambered heads using only modest domed pistions due to the larger displacement of the 454.

Most 396. 402, and 427 replacement domed pistons are designed to work with closed chambered heads. And 454 domed pistons are set up for open chambered heads.

The "good Oval Ports" (049 and 781) will flow as well as the rectangle ports up to 0.550" lift. And in most cases, the ovals will out perform the rectangle ports especially if a little head work is done on the ovals. Just look for 049 and 781 casting numbers on the heads before buying.

Open chamber heads flow a little better than closed due to less material around the valves....the number you are looking for is the casting number under the valve cover. Look at the last 3 numbers in the casting number, .......781, ......049.

I recently had some bigger valves install in a set of stock 402 heads and did a little bowl work. The heads flowed 250 cfm on the intake at 0.500" and 199 cfm on the exhaust. Should be enough for 500hp. The stock 402 heads you have might be enough with some modifications.

On a 396 CI engine, I do not see were this thig could make any compression at all. An open chamber, or chamber of over 110 cc's can't make any compression in a small displacement BBC. Gotta get those bad boys down under 100.
Early high perf closed chamber heads like 201's are being cut down to obtain around 90 cc's and being used on 454's with flat tops.
We would never consider this size chamber in a SBC 400 right? Absolutely not, So why would we consider this in a small displacement BBC? We would not.
Oval port would be the way to go, simply because a rectangle port has a larger port and will stall the air entering the cylinder. This larger port will be too large for a small displacement engine.
Oval port is a wise choice, and your combustion chamber will dictate your compression ratio. Now I am assuming a .040 head gasket and a flat top piston with valve reliefs. Domes, zero deck heigth, and a thinner head gasket will all contribute to greater compression.
Since you are gonna run this on pump gas, you will need to keep a reasonable ratio, but I get away with over 10.5:1 on a big, big block chevy on pump gas and 32* of timing.
FWIW, I run a 540 CI BBC with AFR 357 heads and these have a 119 cc combustion chamber.

Carb Jets - L78
Also note that the 427CID/430HP motors used a stager jetting set-up. This tuned for a better fuel to air ratio for long and short runner divided plenium Hi-riser intakes. The factory reccomended set-up is as follows...

Left Front Jet #78
Right Front Jet #74
Left Rear Jet #80
Right Rear Jet #82

Now keep in mind that with headers or cam you will need to richen these jets up a size or two or three. Change all jets up or down by the same numerical size...(All up 1 size or all up 2 sizes or all back down 1 size ect). Keep the stager sizing the same.

The engineers spent a little more $Bucks tunning these big guys and the L78's and LS6's can benifit from these fine tunning tricks.

Reading spark plugs will be a big help in getting it right.

My L78 runs much better and I get a much more consistant read on my plugs with the staggered jet set-up.

CARB TRICK:
My neighbor runs a 70 SS 396. 12.5-1s, solid lift .629 lift cam, headers, Holley strip dominator, high stall converter and 3.73s. Engine has a nice idle to it. Feels real strong. He has a 950 Holley on it currently, but seems to run very rich at an idle. The rear bumper gets sooty and your eyes tear like crazy. I let me borrow my 750 double pumper and it seems to run much better with the smaller CFM.....I have a feeling that the 750 might be too small for his application though. And the 950 seems too big to me. Any big block Chevy guys here that can enlighten me on what a 396 likes as far as CFM, what sort of jets/ power valve I should run etc?

He needs to put a .015 wire in the idle feed restrictor to eliminate the fat idle and mid range condition that most holley carbs have. I learned this first hand by using the innovate LM-1 air fuel ratio meter this summer, it is the only way to clean up the idle. You wil be amazed at what this does to the idle and crusie air fuel ratio. Most guys try and rejet to get it to lean out at idle. Look at an exploded view of a holley metering block to find out exactly where the brass idle feed restrictors are located (to hard to describe here), bend one end of the wire and the gasket will hold it from moving, you can always take it out with no permanent damage. .015 wire can be purchased at hobby shops for 3 bucks for 12 feet, you need 1 inch! Only put the wire in the primary metering block unless you have a four corner idle carb, then do both metering blocks...you wont even need 1 inch, the bend only stops it from going in to far, you will see how long it needs to be once you get the metering block apart. the gasket then goes on. You will be amazed at the hole shot improvement!

Some History of Nova
1968 Chevrolet, conforming with the popular muscle car formula of a relatively long hood and a short rear deck, introduced the 1968 Nova and launched itself right into the hearts of those who wanted a subtle, yet effective street stomper. Small SS badges on the grille and between the rear taillights were the only tips that this was anything but granny's grocery getter.
The 1968 Nova was the first of its kind to receive an infusion of big-block power. Only two big blocks were assigned to the Nova - the L34 350 horsepower (234 built), and the L78 375 horsepower (667 built). Because of their obvious rarity, they are highly sought after today by Nova enthusiasts.
The L78 was doing well in the NHRA manual stock classes since its introduction in April of 1968. Fred Gibb was a drag racer and Chevrolet dealership owner so he convinced Chevrolet performance engineer Vince Piggins to install the TH400 automatic transmission in L78 Novas so they could compete in the NHRA automatic classes also. NHRA required at least 50 cars be built and available to the general public before they would recognize them as stock for the automatic class. The 50 L78's with the TH400 (COPO 9738) were built during the first two weeks of July 1968 and delivered to Gibb's Chevrolet dealership in LaHarpe, IL, on or before July 15, 1968.

1969 Powering the base 1969 Nova Super Sport was a 300 horsepower 350 incher (up five horsepower over the previous year) that could be had for the first time with a three-speed Turbo Hydromatic transmission. The 350 was revised internally, too, with stronger main bearing bulkheads and caps that were retained with four bolts rather than two.
News of the L78 Nova combination traveled fast amongst the street savvy Bow-Tie believers, and production was way up over the previous year with 5,262 of them being unleashed on the otherwise unsuspecting public. Road tests of the L78 Nova showed it had the right stuff for doing battle on the boulevards. Even with skimpy E-70 tires and a 3.55 gear, mid 14's at more than 101 mph were easily attainable. Some tuning, headers, a 4.10 gear and more tire would put the Nova in the mid to low 13's.

1970 Nova fans are sure to lament 1970 as the last year for the Rat-engined compact. When it came time to appease the ever-tightening requirements of the insurance companies and government horsepower Gestapo, the Nova was the first on the chopping block. Even so, its final year with big-block motivation under the hood is one to be well remembered.
The big-block was certainly nothing new to the Nova lineup, having been introduced as a factory option when Chevy brought out the current body style on 1968. The hot setup was the L78 version of the 396, churning out 375 very strong horses. Now in its third year of production, the L78 Nova wasn't the well-kept secret that it once was and each passing year saw it produced in more prolific numbers. As in previous years, the hottest 396 outnumbered the still respectable 350 horsepower version, and in 1970 it accounted for 3,765 units compared to 1,802 Novas delivered with the "smaller" of the two big-blocks.

Mechanically, the L78 engine remained much the same as in the previous years, the only exceptions being an slight overbore (to actually displace 402 cubic inches) and a new intake manifold. While it still mounted a Holley carb, the intake was reconfigured to clear lowered hood lines on other Chevrolet models. And while the Nova still had more than adequate hood clearance, the smog certification for the L78 was completed with the new "low-rise" intake in place. Of course, the base powerplant for the SS Nova was a very capable 300 horsepower 350 small-block, especially when you consider its 3300 pound weight. In stock form, the SS 350 Nova was good for respectable 15 second clockings while the 375 horsepower big-block version was coaxed into the 13's quite easily.

Anyone but the most ardent Nova fancier would have an extremely difficult time discerning between the 1969 and 1970 versions; a slight taillight revision (larger lenses with the backup lamp moved to the middle of the lens) is probably the most evident clue. Super Sport insignia was still found on both the grille and rear cove areas (along with a blacked-out treatment), but that's about it. The downplayed visuals made the Nova a sleeper in the truest sense of the word and undoubtedly account for its popularity amongst the serious street runners. But they would have to find a new favorite for the coming year; the big-block Nova would be out of the performance picture for 1971. In fact, 1971 would bring about some tremendous changes for the performance enthusiast - none of them for the better. Unquestionably, 1970 will forever be regarded as the high point of Nova (and Chevrolet) performance.

OIL:

Veno - Tech Team Veno

There are 3 type of synthetics, group 3, 4 and 5 .. Group 2 oils are Valvoline VR1 and Penzzoil GT performance, shell Rotela T
Group three oils are Crude refined to group 2 oils then bombarded with hydrogen peroxide to strip off extra Oxygen. atoms to create a group3 oil.. like castrol GTX, Group 4 and 5 oils are 100% manufactured oil... group4 and 5 oils are call PAO's polly alpha olefin's true man made oil... like Mobil1

Oils suitable for breakin……..that are available. with enough Zinc and Phophorus.. OILS LISTED BY ALPHABETICAL ORDER NOT BY QUALITY or quantity of content.

Brad penn break in oil grp2
Joe Gibbs break in oil grp2
Pennzoil GT performance. All weights. grp2
Shell Rotela T 30wt, 40wt, 15W40wt. grp2
Starbright 30Wt grp2
Starbright 40Wt (pending) grp2
Valvoline VR1.. all weights grp2
.
I like the Rotela because of the extra dispersant's and detergents… it creates a higher viscous… and will suspend small particles I also like the StarBright because of the 1600ppm of zinc and is as cheap as Rotela

OILS suitable for street High performance use with enough Zinc and Phosphorus for flat cams and High spring rates. Up to 150lbs seat pressure.

Brad Penn all weights grp2
Castrol GT 20W50 for older cars grp??
Champion XPS 20W50 grp3 syn
Joe Gibbs oils grp??
Mobil1 15W50 gold cap and silver cap. grp4 syn
Mobil1 Turbo diesel truck grp4 syn
Mogil1 racing grp4 syn
Pennzoil GT 25W50 grp2
Royal Purple racing oils syn
Shell Rotela T 30wt, 40wt, 15W40wt. grp2
Quaker State Q horse power 10w60 only grp 3 syn
Valvoline VR1 all weights grp2

TRACK/RACE only.

Brad Penn all weights grp2
Champion XPS 20W50 grp3 syn.
Joe Gibbs oils grp??
Mobil1 racing grp4 syn
Pennzoil GT all weights grp2
Royal Purple racing oil all weights grp4 syn
Quaker State Q RACING all weights…syn
Valvoline VR1 all weights grp2
Valvoline synthetic racing all weights grp?
Valvoline conventional NSL all weights grp2

Pour on top additives to boost zinc
ZDDPLUS, GM EOS, CRANE CAMS BREAK IN, COMP CAMS BREAK IN