Chris, this will entirely depend on how the engine was prepared for this long storage period.
After six years, it's very unlikely that anyone is going to have the details as to what all had been done six years ago.
Ideally, it would have undergone an oil/fiter change (and then run), the fuel would have been completely removed from the system and carburetor (or FI system), and the cylinders would have been properly fogged.
The sea water pump impeller would have been removed (if they really intended for a six year lay up)
At this point, about all you can do is first check the condition of the old fuel (six years usually kills fuel).
Drain and clean and replace if need be.
Dump the contents of the fuel filter into a clean white container, and examine it.
Replace the filter cartridge with fresh fuel in it.
If you prime the fuel delivery system, perhaps use an oil enriched fuel mixture.
Pull the sea water pump and look at the impeller.
An impeller that has been left in the pump housing for six years is no doubt ruined by now.
See if the engine will turn over freely.
Attempt to start it up.
Warm the engine to operating temperature.
Listen for any sounds that should not exist.
After it has been run, you may want to take cylinder pressure readings (i.e., a comression test).
Unitl we know which engine this, we can't suggest what these numbers should be.
Suggestion: If it does not want to fire up, and you begin trouble-shooting, investigate one item only at a time.
If you start pulling several things apart all at once, you'll be at a disadvantage, IMO.
Side note: even after a six year lay up, the crankshaft and cam bearing journals will still have a thin film of oil protection on them.
The cylinders may be somewhat dry of oil, and the cam followers have perhaps bled down some.
I believe that the down side regarding this is somewhat exagerated.
If you are concerned, and if this engine's distributor drives the oil pump, this will need to be removed so that an oiling system primer tool can be used. The risk is a change to the ignition timing when reinstalling.
If this is a V engine, oiling the cylinders is somewhat misunderstood, because gravity pulls the oil to the low side of the ring landings.
If you do this, use a spray oil, and hope that it coats the cylinder walls.
Good luck.
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