Ha, I think I have your set up now, 1965 and water cooled stern glands. Dear old soul.
I am thinking you may well have a cuckoo in the nest here re the greaser.
I well remember back then those water cooled stern glands and a lot of ships of that size were fitted with flow indicators , a lot of the power boats had on deck in the scuppers in a corner a half inch Stainless Steel pipe like a small walking stick radius discharging salt water into the purpose built drain and thence over the side for all to view.
This was sometimes teed off the secondary sea water coolant system, via the watercooled exhaust manifold and thence to the main exhaust sea water injection bend and thence back into the sea via the transom.
Your two blanking plugs, I wonder if one was at one time an inlet for sea water and the other to a tell tale device to show you a flow was occurring?
Perhaps the feed pipe is still there, hidden and blanked off?
Can't figure the greaser angle, did some wag fit it as an after thought?
Of that era the outboard bearing would possibly be white metal or Tufnol turned material, watercooled which then leaves only the packing which lubed by water does not normally require a greaser?
A tiny drip is the necessary indicator for the packing that all is ok.
Thinking about the water feed to the stern gland I suppose a gauge on a pipe from the second fitting ( the one to the prop end ) or a sight glass with a float in it or even a visual one would suffice.
Be interested in whether the stern gland was originally set up for a water feed by locating that blanked off and hidden pipe.
What you got pushing the shaft around?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.