ORIGINAL: BMatthews
No you can't figure it out like that.
It's just way easier to buy the props and try them. Keep in mind too that each airplane will run with varying slippage rate on the props. A "dirty" biplane with lots of rigging and hig drag may be flying with the props showing a 60% to 70% true speed to prop/rpm speed while a slippery skinny racer model may be able to run with a 75% to 85% slippage ratio that lets the prop unload more in the air to a higher speed. At least you specified ground RPM to try to avoid muddying the waters that way.
I would hope the different props being used would at least be in the engines suggested rpm range. The term "ballpark" was used because of the hp curve. The prop load factor provided by the program would also help with an educated guess. Of course the actual test with a particular prop would give the real answer.
I thought that 10% prop slippage would be optimal on a clean aircraft. Not confusing slippage with efficiency.