As long as the engine doesn't try to "run-on" when the ignition switch is turned off, idle speed can be set pretty much where you like it to be. Idle speed that's too high can cause an engine to "Diesel" from compression ignition which can damage pistons, etc. Above 800 RPM, you're probably going to be getting into the intermediate fuel range between idle and high speed, so the idle mixture screw adjustment might not be very effective.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!