Well, it kinda depends. If it's just a stock MII suspension, well.. I imagine it would handle somewhat like a V8 Mustang 2...
Now then, if it's something like the r&c kit... it will have coilovers (this is a good thing), it will have power disc brakes (very good thing), and it will also probably have power rack and pinion (awesome.)...
These coupled together, along with the fact that coilovers are adjustable to fit you needs, pretty much means that you could make that car an autox or open track monster. You have the parts there, it's just a matter of getting it correctly set up. Isn't that always the issue with mustangs though?
-M