The compression relaease is a little piece on the cam gear that slightly bumps the exhaust valve open..Why would that have any effect on the idle ? I disabled it on the one I converted for easier hand starting, but don't remember if the idle was too fast...2 stroke gasser 25s don't idle much slower than about 1600 and it doesn't seem to be a problem...
Taking the cover off won't hurt the gasket...
Just did a search, mine idled at 1400 with a Mejzlik 18-6, top rpm was 7500....4 1/2 lbs...Not as strong as a G23, and heavier...Good for a big slow airplane...