I have a '72 Valiant also with factory disc brakes . I deleted the booster and installed a m.c. from a '73-76 Valiant/Dart without power . The front port in m.c. goes to the rear brakes and the rear port goes to the front brakes in both applications . The distribution block on the fenderwell is also the same for both . The front port in the m.c. goes to the top port in the block . The exit port in the block is facing the rear . The rest you can figure yourself . The reason the resivoir on the rear is larger is because disc brakes require more volume than drums . BTW all brake lines are 3/16ths . Hope this helps , good luck , Tom