I just picked up a used SuperTigre .45 from a friend including a Davis Diesel head for it.
Fuel--- Davis ABC
Prop---Zinger 12x6-10
RPM---9,080
Throttle setting, about 75%, any more and it would labor and slow down.
Muffler- SuperTigre silent.

Hobbsy just as a fling will run the same prop on my ST40 ringed davis head lets see how close my guess 8500 will let you guys know