V20 with a 140 johnson

[thebottomfish]

Before putting this stainless on(last weekend) I had a aluminum 13.75x15 on there and that turned 5300 and 31mph, I really just wanted to see how the boat reacted to the switch in stainless.
Definitely a better bite and acceleration, will have to try going down in pitch to get the rpms up.
If I go from a 13.75x15 3 blade aluminum, what should I shoot for as a 4 blade? I assume I decrease diameter and then obviously I'll want to drop pitch. Would an aluminum 13.25x13 4 blade be a good starting point?