Originally Posted by JimN
That's easy enough to check. If the motor is intact, but bad internally, why not buy a short block and a new OEM intake manifold (it came with a good manifold- an aftermarket won't be better, really) and swap everything? That way, you don't have to question whether the ECM needs to be re-programmed, the motor is correct for the model of boat, etc? That kind of swap os pretty easy. It would be cheaper, too.
And to go along with Jim's line of thought...
You'd probably be better of with a short block or just a rebuild rather then swapping in a different motor, harness and ECM unless you repower it with something MC put in that boat in the first place. But I can't see a need to repower it.