1 ton brake help

I have an 88 cherokee. Recently swapped in a dana 60 and ford 10.25. Big discs up front and drums in the rear. The problem is i have very little braking power. Everythings been powerbled and still no brakes till right at the end of the pedal stroke. Swapped in the e350 master and it made no difference. Feels as if theres air in the system but ive powerbled them 3 times. Im completley stumped any ideas would be appreciated.

did you adjust the rear brake shoes? the drum should be almost difficult to turn by hand, then backed off just a hair. warped front discs can cause the same thing by pushing the pads back out too far. but you would feel that in the pedal.

Swap in the dual diaphragm booster from a later model XJ and step up to a 2500 MC or go hydroboost. I've got the large twin piston 1-ton Ford calipers up front and the Chevy single pistons out back and its stops well with dual diaphragm booster and the 2500 (1-1/4" bore) MC, but not as good as a buddies hydroboost setup with the same calipers.
I also think your setup is obviously requiring much more fluid volume than stock brakes and I don't think that the 1-1/8" bore E350 is large enough, especially with those large drum brake rears.

But the ford f 350 that had the diffs in it uses the same master with 1.125 bore does it not?