I have done a short term re-ring job with up to .008" of cylinder taper. I try to keep taper under .005" if I want a fairly long-life job. On a daily driver, that ring job in a badly tapered cylinder might last a year before the rings lost their tension from excessive flexing. On a freshly bored and honed cylinder, there's virtually no ring flex because there's no change in cylinder diameter as the piston travels from top to bottom.
A good dial bore gauge will show you that almost all cylinder wear happens in the top 1 1/2" of the cylinder, where the compression and combustion pressure is pushing the rings tight against the cylinder walls. Near the bottom of the piston travel even an engine with worn out rings will have little if any cylinder wear.
I assume you've been dealing with 2-stroke motorcycle engines, right? Mosquito foggers don't have much tolerance on ring gap because they compress the crankcase on the downstroke of the piston. The rings are also pinned into place to avoid the ends of the rings hanging up in the transfer ports.
Jerry
