I have chance to buy a 99 grand prix n/a and want to supercharg it.  Any info would be appreciated

Is there a v8 that i can put in my 99 grand prix inplace of its 3.8l non superchared engine 

My first reaction is it MAY be possible to take a Northstar V8 from a Bonneville and transplant it into a GP. Having said that, I don't know of anyone that has done that. However, given that GM produced the FWD V8-powered Bonneville, it stands to reason that with some mad fabrication and engineering skills, someone ought to be able to make it fit. However, this is no bolt in kit to do it. You are completely on your own.

Similarly, people have successfully taken an LS1 and used the components from a more modern Impala and put them in a Pontiac Transport. So putting it into a GP again should not be that big a stretch. Again, there is still no aftermarket, bolt-in kit for this. This requires picking and choosing the right parts and fabrication skills.

What about using a supercharged 3800 instead of the regular 3800? Hood clearance problem? Maybe. Clearly you will need to upgrade the fuel injectors and ECM and perhaps the fuel pump, but not much else I don't think.