Help me complete my build.

I guess I miss the logic of building the car to break the rear...lol. But as we've said.. It aint my car...lol. Good on the disk brakes. If you want larger tires, wider is nice, but taller get's a larger and more stable footprint. In regard to the trans, either will hold it, the 200R4 is smaller, lighter, and can be built strong enough.
Also, don't forget, IIRC 9.99 or faster needs a competition license and Dr. certified good bill of health.