Crooklyn

I'm building a jet boat using the RDX motor and in doing this I require a different exhaust manifold. Can I just block off the cooling ports in & out on the new exhaust manifold that I build? I basically just wont cut those openings into the new face of the manifold.
Will it effect any type of coolant flow to the block itself, if those ports are not in use?
I will be building be boxing in the exhaust pipes and using raw water to keep the engine bay cool.

Racerryan

maybe @KenB350z can answer??