RE: Swap Meet Find
They don't run all that well stock. Change the head, piston, sleeve, bearings, exhaust adapter, modify the rotor, and cut down the mini-pipe and you have one ready to run.
In full race trim, they should turn an 8 1/4 x 7 1/2 prop around 22,500. In a clean airplane, they unload to above 27K. That is the big advantage of high nitro and no tuned pipe. Put the airplane in a slight dive and they will reach around 30K.
Changing from 65% to 15% will drop around 1000 rpm. Stock over race setup another 1500 or so.