Rear disk conversion issue

I have rear discs in the dart. The fronts are 73+ A body single piston and the rear are 94 mustang Cobra csingle.pisyon calipers. The master is a 15/16 without a prop valve. All from Dr. diff.

Disc brakes do take more volume to work. Since you have power brakes, step up to the next size MC and see if you like that feel better.