[dwcsr]

The short answer is what ever fits. Long answer is 292 Chevy 6 is an easier swap and a good one. keeps your original steering box in its original position. You can do a T5 or auto trans,

LS or SBC is harder and the steering box may have to be changed. Your best bet is to search through the threads here. If its been done its here.

I always thought a 4.2 GM I6 would be a nice swap. economy, late model engine EFI and fairly easy to make fit.