No friggen way. Suspension setups aside (which is another can of worms for the GT500) the GT500 has a huge amount of weight to shed to be truly competitive.... In a straight line, and ESPECIALLY in the twisties. The C6 chassis is just WAY better than the GT500.
Take a look at the performance difference between the equal horsepower C6 Z06 and GT500. Night and day.
IMO the vette is a much better all-arounder, and is truly in the exotic league when it comes to a true sports-car. If you are looking for something to modify and care more about the straight line performance, get the GT500.
EDIT:
Side note. Kudos to Ford for stepping up their game on the v-6 stang. The new Camaro has the current v6 stang HANDILY covered, in fact it wasn't even a competition. However if Ford really comes through with this V6, I think the edge goes back to Ford for the V6s.