That Sailfish is a lot of load for twin F150s.
We run PowerTech 15.25"x16" 3-blade props. Better overall for us than the "Black SS" 13.75"x17" that were installed when we repowered in late 2005.
You may have to run 15" pitch to make sure you can get up to (or at least very near) the 6,000RPM mark at WOT with a light load. If you can't do that, then you are overpropped and 'lugging' the engines throughout the speed range.
They are really great engines. Just make sure you follow the break-in procedure carefully to get everything seated properly.
We have 1040-hrs on our twins now, and running great.
Brian