As a reference, my 160 is turning in the 7700 plus rpm range on 15% nitro and a 17X13 APC. I like to leave my top point of the mixture a touch on the rich side. Idle should easily be around 2000 - 2200 rpm. I really don't bother with taching my motors much. I listen to the engine and observe the exhaust smoke trail. Make sure your pushrod on the mixture side does not flex a lot. Sooner or later from wear and tear the mixture side barrel may get stiff causing enough resistance to make the pushrod flex and not give you a consistant mixture. You also need to listen to the engine in the air. Listen for a harsh sound at various throttle settings(usually in the 1/4 to 1/2 throttle position) that almost sounds like a pushrod rattling. I it does you need to richen a few points on the mixture curve(usually the 1st 3 points on a 10X 7 pt mix).

Make sure you get ample cooling directed to the main bearing and the pump area.