[Goat Blower]

As I mentioned above, measure the largest piston, bore off of that measurement, the others can only be looser.

Stock pistons don't expand much at all, so being tight isn't much of a concern. Back in the day, JE pistons had a reputation for growing quite a bit because of the material they used, and PtW needed to be really loose to compensate. Needless to say, there was audible piston slap when they were cold.