That's only 0.07 mm, which is not very significant. For estimating Compression Ratio, you can just use the average. Piston rock doesn't apply as that only occurs in operation (and will average out in any case)


Better yet you can directly measure the piston height re Compression Ratio when you measure the piston dish. Smear some grease around the edge of the piston (down in the rings lands) then put plexiglass over the bore and see how many CCs it takes

You gotta measure dish, right? So do it all in one measurement. This measures the CCs of the Piston Dish + CCs due to Piston Height


After measurement, rotate the piston down and wipe off the excess grease