220 is excellent, especially for an engine with 300k+ miles on it. On the NSX, 215+ (virtually brand-new engine compression) is a very healthy and well-maintained engine; 195-215 is good; 180-195 is fair, and below 180 is within Honda's "OK" spec, but usually a sign of poor maintenance (lack of oil changes) and/or forced induction/nitrous in its past. Btw, these are sea level numbers. When Acura tested my car after the HG repair, they got 185 across the board at 5,500 ft altitude. Converted, that is 212 at sea level, which tracked with the car's history, as my NSX had an oil change at every 5,000 miles since 1992.
The way to rule out rings is to put a tablespoon of motor oil in your low cylinder and re-run the test. If it's back up around 215-220, you know it's the rings. If it is still 205, it's the valves either sticking or out of adjustment.