Use 15% cool power and a light wood prop (Skorepa or similar) 16x6 or 17x6 for fast spool. If you are going to do extended hover practice and want optimal performance I recommend a pump or regulated fuel system (though have no experience with the AX120 with fuel system).
The motor should pull a solid 15 pounds of thrust close to sea level--if you come in @ 8.5 pounds and are not too high you should be good.

I have been on the fence about trying one of these, I have the OS108 and OS160 and they 3D great.