---

Did the water drain out? Is the boat normally stored on a trailer or other dry storage?

If the water drains completely with the garboard drain open I would not be concerned about damage.

The engine RPM and boat speed would be a deal killer to me unless resolved or unless the price is so low that major engine work could be done without wallet pain.

Having said all the above the speed/RPM issue is probably resolvable by installing the right propeller and/or adjusting the engine mounting height to the optimum position.

I recommend that any offer you make be subject to a survey and an engine inspection including a compression check and ECU/ECM report done by a Mercury Marine Certified Technician.

You didn't mention the year the engine was manufactured and the number of hours the engine has been operated.