[JSeery]

Something sounds very strange about this whole issue. The normal procedure is first you acquire the pistons you are wanting to use. Then bore/hone the cylinders to match the pistons. I see no way possible a machinist would not know the size of the pistons and the size of the cylinders. These two factors are needed before you purchase rings! Almost sounds like there is some guessing going on somewhere, am I not understanding the situation?

At the very least, you need to back up at this point and measure things so you know where you are. There should be no "guessing" as to what piston size you have, or what cylinder size you are working with! After establishing sizing, put the pistons in the cylinders and measure the clearance between the piston and cylinder wall. Order the correct rings based on the correct piston size.

Engine rebuild manuals will show how to measure piston/cylinder clearance. But still a little difficult to believe a machinist doesn't understand all of this.