First, running your engine too hot is not good for it. I think your engine is not yet broken in, or you are using a fuel with too little oil, or both. As far as props go, I'm not familiar with your engine. I saw an LA 10 run on an APC 7 x 5 today and was not impressed. I advised going to a 7 x 4, but they did not put up another flight so I can't say how it came out. My experience has been with TD 09's which I have run a lot and tried a bunch of different props on. The Cox 7 x 3.5 has been the best. When I run out of those, I'm going to try a 7 x 3 APC. I would think an OS 10 would be happy turning some RPM's , but that's just a guess, I suppose.

Jim