A Crew Cab Tempest Custom S... DO IT.
Also, don't overlook the stock drivetrain. If it has the OHC I6, fulfill one of my dreams and convert it to MPFI and add a honkin' turbo.
If it's a Pontiac V8, even if it's a 350, you can make great power out of them. They are as stout as the day is long. Best part: Poncho V8's are like Legos; you can mix and match parts to build a powerful Ponti-Mutt! This is what I did with my Trans Am. It has a 1974 400 block, 1971 GTO 400 heads, and a 1968 350 H.O. nodular crank and rods. 1968-1979 stuff is largely interchangeable. Get some block and head casting numbers and post them up!
This site has some great info on Pontiac V8 casting numbers: http://www.wallaceracing.com/head1.htm
