You'll need to have a tune or PCM swap as well. You won't be able to run that motor on the GTP tune. If you like the idea of the tune and don't mind some wrench work, pull the Supercharger, Heads, and Lower Intake Manifold. Have the heads checked over and make sure they weren't the problem with the motor and if they check out swap them over onto the NA motor.
You will need to make a intake so it can breathe better, and get some headers so it can flow well, but you'd be back to the same power.

search "top swap" and you can get lots of info on it
http://www.grandprixforums.net/top-s...info-7763.html