Welcome to the PY forum !
A '70-up Pontiac V8 is the easiest swap. Can use the 301 mounts.
I prefer to see only Pontiac engines in '81 & older Pontiacs. We're about the same age, but I started & stayed with Pontiac power. So, I'm a genuine old school Pontiac freak, and don't plan to change.
Opinions differ.