prop selection for HPR 115

[H2OCamel]

I have (2) HPR 115 and I would like to use prop shops 3, 4 or 5 blade cleaver props for looks. I have twin 1515 2d nue on 4 s and would like to know what props would work? I see some of the large gas HPR run the 5 blade props. Is there a rule of thumb for adding blades? decrease size a % for each additional blade?

I sport run. right now I run x442 rl 2 blade props and get 50+mph wich is just fine for speed so staying the same is ok.
thanks in advance for your help and suggestions.
Chris