To be honest, I haven't done much in a long time, parts got cheap and not many rering jobs come by anymore.
However, I used to take a new ring and a feeler gauge, typically a crushed land would be readily apparent, and if was looser than .004-ish plus a new ring, we'd say they were loose.
I'd think the ball end gauges would be even more effective and much quicker to check around the whole piston