chevy, olds, buick?

That car came with the Olds bolt pattern ONLY. So you will have to use the Olds 350. HOWEVER, you can get a tranny out of a Monte Carlo, or a Gran Prix, an slide a Chevy 350 motor in there, IF you want to change the exhaust, wire harness and if I am not mistaken, the fuel pumps are on opposite sited of the block, so you would have to reroute the lines. I would find a Olds 350 and be done with it.

I agree on the transmission; if you don't find a dual-pattern bellhousing in that car, a Chevy pattern slushbox must be procured. If I recall, however, the fuel pump is on the same side as a SBC, just a little relocated and harder to get at on the Olds, so probably all that will be needed is a different length of rubber hose to connect the pump to the steel line.

There should be no problem swapping the carb and emissions equipment onto the Chevy mill (assuming the manifold is compatible, ie., 2bbl or 4bbl, and the same style EGR (negative or positive backpressure) valve is retained) but it should be noted that a BOP (incl Cad) HEI distributor will *not* fit a Chevy. If a computer control system is being retained, a Chevrolet 7-pin HEI must be obtained (7 pins on the internal module, with a weatherpack pigtail (in addition to the cap connector) hanging out the back of the dizzy. The distributor will not have a centrifugal advance mechanism.) It should also be noted that the appropriate PROM or ECM may be needed to assure smog compliance and driveability with the different engine. If smog compliance is not a requisite, an older 4-pin HEI (has centrifugal advance, no weatherpack connector) and non-ECM carb will serve. If this route is chosen, the only electrical connections will be the starter, power to the HEI, alternator, and oil/water/etc senders, and probably something I forgot. Much of the torturous vacuum hose mess will be disposed of as well.

I cannot speak with certainty on the exhaust concern, but if SBC exhaust manifolds from another B-body ('77-'90 Caprice/Impala, for example) are sourced, the outlets should match your existing Y-pipe.