Ifmoriginal, defintely NOT a Chevy engine in '78. I believe a few were sold in Cal with 305. if it says "Formula 400", it's a Pontiac 400. Spounds pretty rough, though.
If you buy a Camaro, the 454 would be fine. If you get a Firebird, the entire Pontiac "community" would both shun you, and line up to race for money... (:- Ther is no reason to NOT use the Pontiac engine in a Pontiac. It can and does make more streetable power than most other designs, including BBC. Some of those E-headed 461s are lethal in street trim.
That being said, I like Chevy engines, as long as they're in Chevys!
Jim