I have mine at 10.3" instead of 10.5". It flies very well this way.

I had to put the battery pack in the nose to get the c.g. right with my GMS .76 2C engine.

The full tank is located almost on the C.G. so you do not have to worry about balancing it with a full tank.

I find spoilerons to be almost mandatory.

I would try a Graupner 11x8P ( pusher ) prop with that engine.

I'm running it with the more powerful GMS .76, which gives me unlimited vertical.

With the AX your plane will unload in the air giving it very good speed, but you will not get unlimited vertical.

The plane picks up so much speed with the higher pitch prop anyway, that if you nose straight up under full power, the plane will get very high in the sky before it's lost momentum...

A 10x7 3 bladed pusher prop is also available from Master Airscrew too.