I think a Targa would be cool. Open air without the soft top of a convertible. Great idea. Anythings possible, it's just metal and some rubber!
I wouldn't mind (if the RIGHT wreck presented itself) building a Hemi/Prostreet XF either, or a caged pro-touring track car with a Nascar style V8. Alot of possibilities, given the parts become more plentiful that is.