Try a few props and find out. 10,200 rpm with the APC 13 x 8 is not a bad number - about par or slightly better than an average .91 four-stroke with the same prop.

OS has tended to promote the use of larger props with its two-stroke engines of late - presumably as a "responsible corporate citizen" with respect to noise issues. One can therefore assume that OS has designed these engines to happily handle the prescribed heavier loads without deleterious effect.

There is always "the right prop" for every engine/airframe/pilot combo. Regardless of what good theorycraft may suggest and what the guys at the field might recommend, oftentimes it takes a good day at the field, a few props, a bit of patience and some experimentation to find out just what that "right prop" is.

Good luck and do report back in the interests of science