I bought a boat out of a salvage auction with a cracked block and cracked exhaust manifolds. I am guessing that the engine went under water, but I can't be certain. The boat is in remarkable shape other than the drivetrain. Engine is a 2006 Mercruiser 5.7 black scorpion (330 hp)
I have some milky oil in the vdrive and from what I have read a few oil changes and that will probably be ok. I assume that the water in the vdrive is from the oil cooler freezing so that will get changed.
The oil in the motor appeared brand new, which says that if the boat went under the water the motor was pickled. It is also possible that it was as simple as an improper winterization, but I doubt that as the boat got to the salvage auction in August.
motor turned over fine with the starter before I found the cracked block, but I had no gauges. I could hear a click behind the dash when I put power to it, but had no gauges at any point. When I pushed the master reset switch in the engine compartment I lost power to the key, so I am assuming that the switch is bad.
The bigger problem though is the obvious: the cracked block and exhaust manifolds. Because of this, I must get a new motor. I like to build sbcs and have built several performance motors in cars. My research says I need to get a marine gasket set, but that other than that it should be about the same as an SBC in a car other than the accessories which I already have on the current motor. Given that I need to put a new motor in, and may have fried electronics, what are my options? I can do a stock black scorpion build, but for not much more in parts I may be able to do more. I have thought that perhaps some aluminum heads, a stroker crank, and/or different tuning in the PCM may be good things.
any input is very much appreciated!

I have a perfect running takeout 1997 5.7 roller motor, with new OE exhaust and base heads from 2013. It's not a Black Scorpion, it is a 350 Mag carb engine. The new bits have one very short season on them. If you are near New Hampshire PM.
If the Black Scorpion has better spec heads or cam it would be an easy swap.
Built me a bigger engine.

The 350 black acorpion was 315 hp at 5000 rpm.
the 6.2 l had more hp... fyi

But yes, you can use the pieces you want from the Black Scorpion. Maybe get the Mercruiser manual and go through the diag process on the wiring and sensors. The ecm is likely bad. I also have a complete Thunderbolt V ignition if you want it for some short price, pm me With that you can run it with a carburetor.

Ayuh,..... I'm sure you could build yerself a boat motor,.... But,.....

Ya gotta start out in a very different frame of mind,......

Ya wanta build a Torque Monster, redline 'bout 5 grand,.....

Not a screamin' horsepower monster that would be put in a car,.....

Think Truck motor,...... a big heavy truck, that's always goin' uphill at that,.....