If you don't mind a bit of fabrication then fitting a WRC full cradle is an option and MK Motorsport thinks he has reduced the cost of producing them, he can sell the mounts as well for the pick up point on the car, this allows you to mod it to run any diff that you want (my choice would be ally one from USA spec muscle car) We are fitting the cradle to my car at the moment and you can make the track any width you want and place the geo pretty much where you want it etc.

I would have thought a well linked live axle can be made to handle really well?