I would think that 27P or 28P should acheive your goals. I agree with Brett on the 4B props. Diameter will have some effect as well.

Julie

I have 4 blade 28P rolla's. Perfect condition. I ran them about 4 passes on a cat I had with small shaft 4's before I sold the boat. I need to measure the diameter. I'll make a good deal on them if you think you might need them.