Rick has put a couple of really nice S/Cs on various cars, including his own. He does good work -- check out his car and Joe Gould's GT/CS if you haven't yet.

You can get a good bump in HP on the stock internals -- IIRC Ryan's levels about 500hp is about the most you can go before you might start breaking stuff.

You have 4.10s? Lol, that'll get exciting really fast with a blower!