5 cyl. MB diesel converted to Marine

Howdy,
we have access to a sweet running '83 5 cylinder diesel (in a smashed body) and was thinking about converting it to replace a tired Volvo Penta 4 cylinder gas motor in a 20 ft. speed boat. the motor is a little larger and heavier than the gas motor. The safety and fuel economy would have to be much better.
We will build a fresh water cooled exhaust manifold and use a closed cooling system and use marine water cooled oil coolers.
Adapting the flywheel to take the Volvo out drive shou;d not be too much problem.
Can anybody see any problems --- spirtiual guidence required
Does anybody have any experences doing something similar?
thanks
hank

[engatwork]

I would leave the exhaust manifold alone. The turbo will not work as well if you cool the manifold (exhaust gases) down.

[Buciraco]

I would worry about the gearing and you gonna neesd to change the prop. Does the coastgard aprove such a modification?

-the exhaust manifold will have to be wrapped as per CCG rules
would you recommend any non asbestos wrap

engine revs would be almost the same for the MB diesel and gas Volvo
it might use a bigger prop from the extra torque the MB diesel will put out

I'm not sure about if there is a problem installing any motor in a Canadian vessel good suggestion
hank