There are a few different ways...
Grease works well, I have used Crane Cams assembly lube before (sticky chit!) another way is to pull the shaft plug out of the bottom of the block and use a bent coat hanger.
Perhaps the coolest method I have seen is to drill and tap the timing cover hole inline with pushrod and use a really long timing cover bolt to pinch it like they do on the small blocks (but they use one of the front motor mount bolts).....
The easiest way is to turn the engine upside down.

I know.....The motor is in the boat.

The next easiest way is to throw the mechanical pump away and go Aeromotive electric

GT