:welcome:
Drain the fuel is a good idea. Got a place to dispose of it?
I would also replace the fuel filter, purge the upper fuel line to the carb and take the carb out and clean it with some good solvent/carb cleaner. (assuming it is a carbureted 7.4L)
Take the spark plugs out and see what they look like. Get new as needed.
Squirt some fogging oil into the cylinders via the sparkplug holes, now that you have the spark plugs out
Assuming that the battery is dead. Go get a new battery.
With the spark plugs out and after you have squirted the fogging oil, see if you can get the engine to rotate 'by hand'. If it does, see if you can spin the engine by engaging the starter.
If that works out see if you can engage the starter long enough that oil pressure starts to read on the gauge at the helm. (assuming the oil is at a sufficient level).
You should replace the impeller in the sea water pump (engine lower starboard side) Use soapy water to give the impeller some lubrication for when it first starts spinning.
If you get this far, maybe re-assemble the fuel system and put the spark plugs in and try starting the engine for real. (make sure you got water running to the outdrive).
After all that, go take a nap, because you will be tired
Others will add suggestions, I'm sure. Let us know how things proceed along the way.
