inboard prop

[fat2nawilly]

I'm currently running a 15 1/2''d x 17p on my 23 inboard but have cavitation issues. Ive been told that i should go up in size to a 17d or 18d wheel to help prevent this issue. so my question is if i go to a bigger size wheel what should my pitch be? I have a marine power efi 350 with 315hp and a hurth 1.5-1 trans. also from the tip of my prop to the hull is 3''. any info to solve my issues will be greatly appreciated. thanks in advanced Brian