Measured the bores with a "inch" micrometer that reads 0.0001 (0.00254mm) wrote the numbers down and converted them to metric
bores were nearly perfect with variation of .0001" from top to bottom and another .0001 in the last few centimeters where the sides open up. I remember writing down 54.008 on both cylinders which would be the measurement in the middle so they vary from 54.005 at the top to 54.01 at the very bottom
Manual says C is 54.000-54.005 with service limit 54.075
B is 54.005-54.010 so my cylinder worn out to B standard size?

Now to the piston

C bore needs D piston and the spec is 53.961-53.965 with limit 53.030
I clearly recall measuring and writing this numbers over and over because I had a machinist double check, 53.927 and 53.928, I have very good visual memory, those numbers are quite clear in my mind, and yes 15mm from the bottom, and just a hair under the service limit.

The other pair of cylinders came out of A and B bores that I did not measure but pistons both read 53.947( this one I also recall because I kept checking and re-checking, crossing 7 for 8 etc. these pistons are above the D piston limit of .930 so can they be used in a C bore?