While you are at it plan on replacing the timing cover as it never was painted from the factory because the circulating pump was mounted.
I must beg to differ with All dodge in reference to removing the out drive.
It is easier to separate the engine at the flywheel housing. Hopefully the output shaft splines are not rusted to the flex plate.
If that is the case then you will have to do as Alldodge suggested and remove the 6 bolts that retain the conical ring so that the whole housing will come out with the engine. Good luck
It also goes by the design of the boat. I think some boat builders lay the engine on the floor and see how tight they can get the engine surrounded.
Most time I was able to pull the engine from the bellhousing.
I actually think the boat builders shrink wrap the engine and use it as the plug to make molds..... some boats you need to pull the motor to change starter