That's not like 8 cans of bondo around the back window is it? You may be better off finding a donor to cut a chunk of top out of to build it. But for now it would do. As far as the Pontiac goes, you may run into some issues finding a left manifold that will fit. With the Chev motors you need one that dumps either between the middle and rear exhaust ports, or right at the rear. I'd want to physically measure before I'd say for sure that's the only issue to making it fit.