sswapp, the in-line proportioning valves are not to be used to correct incompatibility between the master and wheel cylinders. It is my understanding that disc/drum combos require a prop valve because your front calipers need different line pressure to initiate braking. I have one on the rear line just for heavy loads (new dual-res master cylinder w/ stock drums). Match up your hardware as Mr. Proffit advised, and the prop valve will allow you to fine tune the front/rear balance.
