You should call Griggs Racing and see what they can put together for you. They build some awesome mustangs. I almost bought one 2 years ago, they offer turnkey models from street to track. If you track the car and from your OP it sounds like you do then check them out.
In the Virginia City Hill climb one year their mustang pulled 1.5 Gs at one point. There are videos on this page of one chasing down a Z06, some laps at Infineon and that Virginia City run.
Imagine they could make a Boss 302 pretty hot!