The bolt pattern for chevy engines is different that it is for BOP (oldsmobile,pontiac, and buick). Cadalliac has the same bolt pattern as BOP. Un less your tranny is a unibolt pattern tranny (meaning that all GM engines will bolt to it) you will have to get a different tranny. The cheapest engine out of all of those to rebuild is going to be the 455 olds. You might run into problems withe the motor mount blocks and might have to do some fabricationto get it to fit. You will also have to get a different fan shoud. If it were me i would consider electric fans.
If you have any other question I'm sure i can answer them for you.

MARK