my brother owns a 79' bonneville 2dr with a 350. I think it recently blew a head gasket. lots of white smoke pouring out of the exhaust and has no power. so we're considering swaping in a 350 out of a newer car with less mileage and hopefully more power. being a ford guy I'm completely clueless when it comes to GM motors and their interchangeability.
so what will fit?

we can get an LT1 out of a 95' camaro locally for pretty cheap. will that work with just swapping over the intake or is it more involved?

we can also get low mileage 84' monte carlo parts car has a 350, 700r4, and a 7.5" posi w/ 373'*. would all this swap over?

thanks ahead of time for any help.

trying to think of who would be knowledgeable on the 350/5.7'*.

The intake manifold will not match up with the heads on the LT1. I believe the LT1 has reverse flow heads....

If your going to do a motor swap with the LT1 you would be looking at wiring harness, bell housing and probably the tranny or at least machining out adapter plates to make the LT1 fit the 79 running gear.

I ran a 79 Bonne back in the day. Mine was a 350 as well, but it was a BUICK 350. I too lost the head gasket shortly after it cleared 100k. I think we need to determine which 350 you have before we can get you an accurate assessment on your swapping question. You could have a Pontiac, Buick, Chevy or an Olds V8 equipped car. GM was notorious for these types of engine installs under their new-at-that-time "Corporate" drivetrains. The LT1 could be swapped in, but it would be labor intensive due to the reverse flow cooling orientation. One would need to check for motor mount compatibility as well. The transmission is more than likely a 200R4 if it came out of an 84 Monte. The 700R4 was never available in the G-body platform. A 700R4 is a bolt in because it was offered in the 80'* vintage B-Bodies. All you would need is the trans crossmember/driveshaft and some other odds/ends for the transplant. The rear end is a no go. You might be able to pirate the guts, but a 94-96 Impala SS or 9C1 (police pkg) would be a better choice. The G-Body diffs are too small in width and their mounts are not compatible with the B-Bodies. I hope this sheds some light.

we picked up a 85 firebird with a rebuilt 350. turns out they're completely different. the bonne 350 has the distributer in the front, mounts are different, tranny bolt pattern is different, and the motor looks alot wider. the firebird 350 has the dizzy in the rear. wtf do we do now. I think the biggest issue is the mounts. are there mounts that will work?

If the distributor is in the front, then it is the Buick 350. You'll have to get motor mounts for the Chevy V8, and that'* an easy fix. The Chevy motor WILL NOT mount up to the tranny in the Bonne either. The bellhousing is entirely different. You'll have to get a THM350 w/ a Chevy bolt pattern. Make sure you use the HEI distributor to make your swap easy. After that, you'll need the exhaust manifolds and crossover for a Chevy B-body and some odds/ends to finish it up. All in all, most of what you'll need can be found in most JY'*.

Just as a side note: If you have a Buick under the hood, you'll most likely have the 12" brake rotors in the front and a 5X5 bolt pattern on the wheels.