The Mustang is always going to handle like a truck. It might be real fast and turn great lap times with the right setup (and don't get caught up in all this drifting nonsense--it's stupid) but it'll still drive like a truck. A friend of mine had one of the original '89 Saleen Mustangs; full cage welded to the frame, lexan rear window, built 302, bigass brakes etc etc etc and the thing was an amazing track car. He turned 1'08" laps at VIR on street tires in it. He kept it for maybe 6 months and then sold it for a '95 BMW M3 Lightweight.

Oh and rotaries aren't that great--they're nice and compact but if you really want to make an RX-7 fly then you drop in a Chevy smallblock.