Steve,
On your other post I had mentioned ghosting. At least that is what I call it. See your pic I reattached below. In the black box is wear on the piston skirt that I call ghosting. Whereas, in the blue areas you can still see the original machine marking from when the piston was manufactured.
I argue that due to high piston to cylinder clearance tolerances, the piston encounters a floating effect as it cycles in the cylinder, which tends to wear the skirt area of the piston significantly more than the upper portion.
At the top of the piston and the sides, this effect is reduced due to the rings holding the piston top correctly in the cylinder, and the fact that the piston doesn't experience torque force from the crankshaft side-to-side.
Due to this ghosting wear, you will most probably have more wear in the cylinder lower portion than the upper. You need to measure as far into the cylinder the ring gap, and measure with a new ring, not the old one. Also, mic the piston and the cylinder to see what the piston to cylinder clearance is. Remember also, the bottom of the cylinder is where the skirt will ride in the cylinder. This area is more insignificant of a measurement, as most likely the rings will never cycle in that portion of the cylinder. There is still a need to have a correct tolerance in that area, I'm just saying to get an accurate ring gap measurement, you should measure where the rings will ride in the cylinder.
I've also attached a pic of my saw piston. This pic is taken at BDC. That means, that is the lowest point in the cycle that the rings will be in the cylinder at any given time during operation. You need to make sure you measure your ring
gap somewhere at and above that point in the cylinder to be entirely accurate with how the machine will function with the piston, ring and cylinder installed. If you have a good measurement with a new ring in that region of the cylinder, then the cylinder is serviceable. If you don't, you'll need a new cylinder.
Hope this helps....Cheers, Dan