Finally got the "expert" to confirm my piston and bore measurements, of course I left all the cylinders behind so I'm doing this from memory...

So I got a pair of "C" cylinders, both measured out at 54.008 which is OK for a C cylinder, correct?
Pistons came out at 53.928 and 53.927, ring end gap 0.45-0.50 on all 4 rings, I assume those pistons are junk and rings were recently replaced? Could this possibly be the rattle I was hearing?

Other set I have is an A and B cylinders, both have scratches on the bore as if the bike ran without an air filter and sucked in some dirt/sand, those pistons measured out both at 53.947-.948, can they be used with "C" cylinders? that will make is 0.06mm gap.

Appreciate any advice
Hope it's OK to discuss piston clearance in the open forum...