It should be able to turn an X-637 with no problem but there are people that have used the X-440/3 but I don't know how they did it without overloading the engine.
I used to have a Grey Thunder with the .16 in it and it cranked the X-637 over just fine. Dump that stock prop and you'll see a lot more speed. The only thing that it does is throw a big roostertail.