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

Are the bleeder screws at the top? I don't know if the left and right can be inadvertently switched? It's worth a look.
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.