Z32 brakes onan s13 question

[xxmexx]

Im getting my calipers ready for the swap and decided to rebuild them. I have removed all the pistons but some of them have small dents around the top rim (they were like that before i removed them) is this a problem? if it is does anyone know where i can buy new pistons.

Second issue with the pistons is they have rust around the top rim. What is a good way to remove this rust without damaging the piston?

Third and final issue. Does anyone know of a place i can buy a 1" master cylider that requires no mods to make it work on a non ABS S13? I have been looking for the last few days with no luck.

[Phlo240]

FR sport.com has a master cylinder.