I think you might like the results you get with a Master Airscrew 12x6 K-Series prop. The K series props are designed for four stroke engines in particular, and feature a wide blade. They provide a terrific amount of thrust and ideal load for high torque engines.

Breaking in your engine according to the recommendations in the owner's manual is always the right thing to do. It sounds like you've been patient and followed all of the right steps to assure smooth performance and long life from your Saito .56 four stroke. Congratulations and enjoy!