Repost the numbers off the prop itself and then include your GPS WOT speed with a normal fishing load and the engine RPM at that speed.

You are probably going to be around an 11X11 or 10.5X12 or somewhere around that.

A 4 blade prop doesn't necessarily perform better than a 3 blade. The 4 generally gives a little better bow lift but sacrifices top speed. It's often worthwhile to contact a dealer that has props you can borrow to try out.