Seeing how old this thread is, I don't know if this idea is still pertinent, but for anyone else that may be considering doing this, there is such a thing as "top-swapping" a supercharged 3.8's heads, intake, harmonic balancer, and other related items onto an otherwise NA 3.8. It's possible, and because of the different pistons in the NA as opposed to the supercharged motor, it will have a higher CR than a stock GTP, and will make slightly more power.
Here's a link to doing just that from the grandprixforums, of which I am also a member!
http://www.grandprixforums.net/threa...s-of-3800-Info
Lots of great info there.