Best Handling Mustang?

I dont think it would be twice the price to make a fox handle like you want it, but from what i've heard the sn95's are a better place to start at for an autocross car. Fox's tend to be much better drag cars than the sn95's though.

Also, this should probably be in talk.

www.MaximumMotorsports.com

You can have your Fox handle 1 lateral G. That's Corvette stlye. Search for a guy named StangBear427 he has an awesome suspension set-up.

Steeda, Kenny Brown, and Griggs are other good suspension company's.

Find a SVO

It depends on how deep you want to go. The truth of the matter is no factory(minus cobra R) mustang is good enough to be competitive in the autocross field. BUT any mustang can be made competative quite easily. now, you still have to fight the fact that you are nose heavy, that you can never get a true 50/50 weight distro, and your cg cant be placed 'idealy'. Withought getting into a huge discussion you can take your mustang and make it capable, the real question is are you. Start with the links already provided. Good luck, and if it were me I would use the foundation I already had