If you are using the right prop you won't be running the engine too fast!

If you start with the needle rich (out) and then screw it in then the RPM will rise to max. At this max RPM most sport flyers will unscrew the needle a tiny bit to make the engine run rich. If you continue to screw in the needle at the max RPM point then the RPM will drop. This is the point at which the engine is running lean. It will overheat but will not be at max RPM.

If you want to check the rough needle setting without a tach then pinch the fuel line hard and then let go. If the RPM rises then the engine is rich and can be leaned out a little. If you pinched the fuel line and let go, and it nearly quit then it is too lean.

Is the prop you are trying balanced? Are you using a spinner? (if so, run it without the spinner and see if it is better). Are you using the same engine mount as before?