Hi!
As You have OS .46 engines the proper 3-blade prop would be a 10x6 , that if you fly at sea level. I don't recommend 3-blade props though as these are always inferior to two bladed ones.

I flew a Marutaka Cessna 310, 25 years ago with Enya .40 X engines and these were much to strong for it. But the airplane was very easy to fly.

Regards!
Jan K
Sweden