I have my heart set on a new 5.0, BUT the GT500's are definitely the way to go since the product knowledge is already there. Its a WINNER either way in my book!
I'd say GT500 if your planning on going forced induction, your already quite a few steps ahead of where you would be. I do like the newer body style but seems smarter to do GT500 IMO.
Like everyone else said, test drive each. Only true way to find what you like more
The other thing to consider besides the obvious styling preference, mod potential, etc., you also should consider future resale value (even though a lot of people say they don't care because they will never sell it:rollseyes) The fact is that even if you never sell, chances are really good that someone will, whether it is your wife, kids, etc. Hands down, the GT500 will hold it's value better down the road, because it wears that "special" Shelby name:rollseyes, and at the end of the day, a GT, is still... just a GT like the other 20,000,000 out there. I also think that because you say you want to supercharge, the choice should be obvious! Why start with a weaker, more limited platform (engine)? With the 500, you are starting at a very respectable hp range, and the sky is the limit. With the regular GT, you will throw a boatload of cash at it, to JUST reach the level that the GT500 starts at! Doesn't make much sense when you look at that way, unless you really prefer the new look better, or just want kind of a sleeper type setup.