Which master cylinder bore size to use for power disc Kelsey/Hayes

Yes they can be installed upside done. Bleeders up. Some of the 70's pads can be installed backwards. A friend of mine wanted to do his own brake job and after taking it for a test drive (I call it seating the pads), he says to me, "they are worst than before". I took a look and YEP, they were metal on metal.
Someone put pads on metal side toward the rotor?