A body power brake master cylinder

I am in need of a master cylinder for my 69 Dart. It has power disc brakes (converted from drum). I have found several numbers, but no one seems to have it in stock. I looked on E-bay and there are a couple with pictures, but they say they might send one that will work, but not look correct, which I don't want. Any idea on getting one? Will one from a 71-76 A body work? Thanks. Aaron.

Bore size is smaller on the later ones. 0.937" vs 1.00". It will work, but you'll have a bit longer pedal travel.

Just longer travel? It won't affect the hardness of the pedal?

With power brakes you probably won't notice it, but it should be a bit softer.

Awesome! Thanks! I just ordered one!