I'm not sure if you can do this on your early YJ, but I bought the 1995 booster and MC for my '92. The '95 uses a dual diaphragm booster, and adds a lot more stopping ability. I also upgraded to braided hoses. Some people have said these are a waste of money, but mine gave me a noticeable increase in stopping uniformly (doesn't pull to one side).
'92 5.2 Magnum SMPFI/AX15/NP231 SYE/HP Dana 44 ARB/8.8 ARB, 4.88 33x10.5-15 KM2's
M.O.R.E. boomerangs, BDS 3.5" springs, FoMoCo fan, FoMoCo Type III injectors, BDO aluminum rockers, HF 8k winch