Looking for Cleaver props
 

I have rebuilt an old Excaliber Cat with Kamma surface drives I currently have 4 blade 19 spline 18 X 29 cleavers RH. I have trouble getting RPMs to come up trying to plane, and then at WOT and a small amount of trim I am not reaching max RPM, I could use about 600 - 1000 more. My thought is that a 25 to 27 pitch would do the trick, not sure. Anyway I can not locate a pair of 18 or 17.5 X 25 to 27 4 blade 19 spline RH Cleavers can anyone help?