Trans is most probably the A-904. It can be rebuilt and upgraded to work fine behind a normal 360 V-8. PLUS it takes less horsepower to run than the A727 does.
One MAIN reason to stay with the A-body engine family is the wiring harness and other things between A-blocks and B/RB-blocks in C-body cars is that so many things are on the opposite sides of the car! Exhaust pipe is one (A-blk = lh side, B-blk = rh side . . . for single exhaust systems. Many other wiring harness "things" too. PLUS, the total weights will be similar so the torsion bars will not need to be adjusted too much.
The 360 has more lower-rpm torque and that will make the car act much better, even with the normal 2.94 rear axle most of them had. Just a good "wrecking yard" engine will be fine, but you'll probably want to see what's "inside it", for good measure, before you install it. Most of the 360s were 2bbls, most having the Holley 2210/2245 versions, except for the 1980 model. The 4bbls were spreadbore Thermoquads, but you don't need that much for a stock engine.
Enjoy!
CBODY67