RE: switch 3 blade prop to 2 blade?
A two-blade prop that is 11x6 would be a good match. You could also go with a 3-blade prop with a steeper pitch to it and also enjoy more power.
Your Alpha .40 trainer with the Evo TPS engine came with a 10x4 3-blade prop. You could simply upgrade your trainer to a 10x6 or 10x7 3-blade prop and not have to buy a new spinner.
Good luck, and good shopping!