Hey Whatto:
You've gotten some great advice here.
The Reverend Dr. Tony says go with the inline engine, unless you're looking for a door slammer.
Just my $.02 worth If I were going to go with a BIG block, I would drop in a 500 caddy, they're plentiful and not as popular as the BBC engines and therefore less expen$ive. Tons of torque.
I took the easy way out and went with a 261 inliner.
BuBBA B52