4 wheel disc brakes

since its the wildwood kits you shouldn't need the prop valve as they are setup with the correct piston diameter's to not over power the rear. Now if you worried about locking the rears up in a panic situation I would install one of these. On a drum car you need to delay and reduce pressure as they work faster and harder than a disc, but on a tuned 4 wheel system you just need to delay the spike so they don't lock up, not reduce.

http://www.dpiracingproducts.com/lock-resistant-brake-system-lbs/