You're going to want to start with a smaller diameter prop until you get a couple of gallons through the .70 RFS to get the ring nice and set. Start with a 13x4 or 13x5 and then move to a 14" prop once you've got a good, reliable idle established.

Once broken in, Flying Freak's suggestion of a 14x4 will be an excellent choice for 3D acrobatics.