This^^. Yes, if you're seeing that much variance from top to bottom, you need to check your cylinder taper- on a true cylinder there should not be any difference in end gap wherever you measure it. It should be the same all the way down the cylinder.
If you must, then measure it at the point that you get the lowest measurement, as 67Dart273 said.
Just got it back from machine shop. It was bored to .040 and heads reworked. Compression ring end gap Measured .020 at about 1 1/2 inch down from the top, it measured .017 at 2 inches from the bottom. Is that to much taper?
