330 Sundancer Prop reccomendation

[NoThanksDad]

I have twin counter rotating 5.7L MerCruisers 230HP each. I'd like to know what the optimum RPM's and can you also make three prop size reccomendations?
1. 4 Blade High end price range
2. 4 Blade Mid price range
3. 4 Blade Lower price range (minimum rec/not cheapest)

Thanks in advance for your help.