Of course, you can run a Pontiac body that came with a Pontiac engine, then use an engine that didn't come in that particular model car.
We have 2 good examples of that.
Carroll Warling has a '74 GTO. I think he runs a '74 400 engine in it, probably very much like the one in his '74 Lemans. I think Norman said he is planning an iron head 428 for it this season. That'll be interesting. I think most of the 428 guys are running the NHRA legal Edelbrock alum heads.
Larry Maxwell has taken another approach. He has a small tire '68 Bird, which looks like a Stocker. He runs the '74 GTO 350 engine. So far, it hasn't been real quick. But, it always runs under it's index. That's as quick as you have to go, to win races.
Larry ran a 10.82 at the Winter Nats. That may be the quickest time I've seen. Most races he's in the low 11's.
https://www.dragracecentral.com/DRCS...r2019#indextop