also used a high pitched prop not a 3d one, this will maxmize the airflow over the engine and help keep it cool
i would use a apc 10x7 for breakin or maybe even a apc 9x8.5
I don't think this is a good idea. You want good airflow over the engine, and when you use a higher pitch prop you just don't get this.
Why? Because a higher pitched prop has more of the blade stalled when it is not moving through the air. The tips are moving air, but that air is outside where the cylinder is located.
Use an 11x5 or 11x6 2-bladed prop for your first few tanks.
Good advice for the initial run. Light load gives a broad needle range. Depending on what the airplane is, I would fly with 11-7 or 12-5 or 12-6 to start with. Also remember to open up the needle half a turn or more when you put on a bigger prop before starting.