Can i swap gto engine and transmission to a grand prix 2000 gtp supercharged body?

First off, remember its an old and relatively worthless car even with a good engine. At the moment its worth scrap value minus the cost of the tow truck to haul it away. (Do you see where I'm going with this?) There are tons of reasonably priced GTPs out there. Find a nice one and buy it. That will cost you about half what it will cost you to rebuild your motor, and that's if you're doing the R&R and most of the engine assembly work yourself. If you have money to burn and just want a hot rod, there are a number of outlets that specialize in performance parts for supercharged 3.8s. Start with ZZ Performance, and join an online Grand Prix forum and do a bunch of research there. There's lots of good info to be had and you can figure out where you're going with this project before you start spending time and money.