What would be a good prop to break this engine on and do 3D aerobatics. The model would probably not weigh more than 10.5 lbs.

You'll want to break the engine in with an 18 x 8 prop. Once it's broken in, tach it. For 3D-type flying, you usually want a prop with lower pitch, but you'll need to keep the RPM level the same. Try a 20 x 6 prop after breakin and see how the model flies.

We're sorry we don't have a specific prop. You'll have to 'play' with different props to see how the model performs. Different brands of propeller, even though they say they're the same diameter and pitch, will give you different performance. The 'try and see' method is the only way to tune the engine to your airframe and performance desires.