Hmm, I am still shy on the use of large diameter draggy props for running in purposes since they do not allow the engine to rev out freely at its most critical time, or in other words - resistance to acceleration puts strain on engine components when they are at their most abrasive time.

I can see the logic behind a larger prop that provides extra flywheel weight for ease of staring but that where the advantage of extra inches of prop blade ends.

Better to use a mechanical weight like heavy hub, lead washer or similar and ditch the aerodynamic drag because the weight stays a constant whereas the drag increases as a square of the speed.