I dont think that changing your prop is going to affect EGT and you cant tell anyting about your prop based on your EGT values. There are too many variables with EGT (like distance from engine, MIXTURE, and calibration) for the absolute values to mean much. My peak is around 1800 as well, which is actually fine. EGT is not used so much for its absolute value, but telling where you are rich or lean of peak. Absolute value can be useful to diagnose a new problem but otherwise it is just another reference for lean or rich of peak EGT.
You cannot make a normally aspirated rotary "work too hard".
If you want to bring to bring down the EGT, enrich the mixture some. But that is not really necessary in a normally aspirated rotary. unless you have done big changes to the engine it can run at peak EGT all day long without problem.
In my plane, running at continuous peak EGT burns out the turbo after about 100 hrs so I make a point to run either rich or lean of peak.
BTW, 6800 ground RPM sounds like plenty. It will go quite a fit faster at altitude. I think I only get about 6000 on the ground at 35"MAP wit the 2.17:1 gear box.
For what it is worth, my prop is a 3 bladed, 64"diameter with a 77" pitch and it is about right for general purpose (but was a little under pitched for racing). None of that means a whole hill of beans because different prop makers rate the props differently and the numbers are not standardized.
Dave Leonard