I had a '66 dart with 4 wheel drums & I swapped the fronts to '76 A discs (2.75 bore) & kept the OE splitter & used a later (BBP) 7&1/4 rear which may have had slightly wider 10" shoes & it stopped flawless & no discernable pad wear after years of driving (but I concede that this was easy DD). It would lockup the rears if I stood on it (rarely needed if I kept my eyes off of the sidewalk & on the road). Joe bypass or open up the prop valve & report what happens.