Flyboy Dave,
You seem to think that because you cannot see the out of round ring, even when you put the ring in the bore and cannot see light that it is perfectly round. Well it's not. Let me through one more bit of information not previously discussed. In fact when most engines run, especially air cooled engines, the cylinder is definitely not round, no mater how close to perfect it was before. It will be hotter on one side than the other, which makes it a bit wider on the hot side. That is one reason it is important to bring the engine up to temp during break in.

While I do not have the engine building experience you do. I am a licensed engineer who has some considerable experience doing thermodynamic, heat loss, and thermal expansion analysis. As an engineer I learned long ago that the ring is sprung with a gap because the dimensions of the cylinder is constantly changing from heat and wear.