I have a 19,(almost 20ft.) Shabah, with a 4.3 6V
I run a high five 19"
These are great props, pulls like no other.
Great for skiing, tubing or alot of people in the boat.
Problem: I bump the rev.limter with it and only have a v6.
If you have a v8, I would have a prop guy pitch it out to a 21"
I think you will also hit the rev. limiter (around 5000 rpms)
Mine will run 5000rpms, 50mph
But great prop, wish mine had a little higher pitch.
Hope this helps,
Jeff