I have a 1980 2QM15 on my Hunter 30. It is a great little engine and I have had no problems over the past 8 years. It is sensitive to fuel flow problems so make sure you bleed the lines when changing filters. Bleeding is easy since there is a bleed screw on top of the secondary filter. The engine is raw water cooled so it does not get very hot - hence you cannot heat water for your galley. There is no engine kill lever - so just decrease the throttle until it dies. There is no tachometer but you can add one run off the alternator. There is no temp gauge so ake sure the cooling system is working well. I would change the: impeller, thermostat, hoses, belts, zincs, temp sensor and oil pressure sensor, and air filter, on an old engine like that.
Thanks for your posting... We ended up buying the Irwin. During the survey, I was able to sea trial her and was impressed by how she handled. To shut down the engine there is a fuel cutoff, similar to what you might find on a small airplane... maybe it was installed by a previous owner.
We plan to cruise the Chesapeake and spend a fair amount of time at anchor, so I''m concerned about the hot water issue for the galley & the shower... do you have hot water on board?
If you are looking to install one, I have 1980 Irwin 34. It has a factory installed water heater which they placed aft of the engine in the engine compartment. its about 18" square (box)and acts as a seat when working on Yanmar