360/440 swap

Welded frame connectors are your friend in any performance application, even small blocks. Welded into the floor is even better. Tied into a roll bar/cage is best, if you go that far.

As for parts other than k-member/Schumacher adapter mounts - trans (bellhousing bolt pattern is different) and radiator. (Inlet/outlets are in different locations and bigger wouldn't hurt.)

Downsides are making it more nose-heavy, tight headers and spark plug access.