Hi people,
DA is probably suggesting which size based on what brand of prop you are going to use. The mejlik will require a 22x10, where the Menz will require a 22x8. The thing with breakin is how much load you apply to the engine. You don't want to overheat during breakin.

Cajun,
You'll find more than power in that beast. The transition, power, and smoothness the DA engines have is really nice. They start so easy too. That's a fine engine you have there...hope you enjoy it. It should last a long long time.