We'd have no idea what prop would get max speed from your airplane/engine combination. We'd prop the engine to turn in the high 11,000's and see which ones gave you the best performance. Because the engine is normally turned below 10,000 RPM, turning it near 12,000 RPM will give you a shortened engine life. Turn much over 12K RPM, and you're going into the "red" area, and could have the engine fail at any point.