Be sure to raise the water box up with about 3.5 inches of Eva block so water doesn't run back and get in your rear cylinder under certain reboarding situations and when loading the ski with the noise up.
Ive tried no fcv, put a 2.0 or 2.5 carb seat in the water box line at the box with a flow control right before it. On jets I've used the 110 all the way down to a 60 in the spray bar.... @ 60 the pipe can get too hot.....185 deg is the max temp of the normal rrp pipes out there. They were trying a higher temp layup last year.
So no easy answer to your question, you'll have to just start at the 110 jet, you can start without a box restricter and fc valve and ride and see how you like it. Then do the water box restricter and fc valve, adjust on trailer so valve opening at higher rpm say 2500 or so to start and ride & see how you like that. Then ride the ski, monitor pipe temps always and start dropping jet size and see what you like. The smaller jet push the power band up in the rpm range
Edit; The other thing I'll mention is getting your engine to operate normally at 140 to 150 deg. I use equal size water restricters in all pisser lines including water box to get my engine operating temp up (as needed),,,, before i start tuning the pipe.
Crimp type clamps on the rrp silicone water hose didn't hold well with restricters, blew hoses off once, I switched over to translucent hose and have to check clamp torque often
Been wanting to try parallel cooling system to bring water pressure down but haven't yet
