If I may make an observation here; I'm not familiar with the Suzi 140 but I feel you guys are maybe thinking in the wrong direction. The motor is about 2lt, normally aspirated and 140hp. That's a good power from a smallish engine and I'd bet the low end torque is not particularly high so the power delivery is going to be a bit peaky. Since most of the time you're not likely to be driving flat out, why not prop the motor for good low to midrange performance, ie. good holding, good acceleration, good grip while climbing the back of a wave etc., all the things ribs should excel at? If it were me, I'd be aiming to choose a prop which runs close to maximum revs when flat out, which I believe is 6200rpm.
Cruising revs will be a bit higher but the throttle will likely be less open because the engine will be lighter loaded and I'd bet you'll see very little difference in fuel consumption. It could even be better. Over pitching for relaxing cruise is a bit like leaving your car in too high a gear for most of your driving and when you come to the hills, you're fekked. It's also not best for the engine.
I used to have the Suzi 200 which was 2.7lt and a long stroke hence high low/mid torque and it's outstanding, and very satisfying, characteristic was mid range grunt. It gave me far more driving pleasure than an extra knot flat out.
It was the same motor that Codprawn has and although I've never spoken to him I'll bet he will confirm my experience.
So, forget the top end, get the midrange right it's just better boating.
Now, the new 150hp Suzi looks interesting cos it's 3ltr. Just 10hp more but I bet it pulls like a train.
Just my thoughts.