Brass oilite bushings are the best most reliable marine shaft seal out there at the best price period .I have a Neptune Sb-1 which leaked from the simital main seal not long after its first run,I replaced it with my own modified stuffing box,now I have zero leaks and go even deeper than the maker suggests,cost 2 bucks!
The secret to making the best stuffing box is is the choice of the right materials,a stainless steel centerless shaft which is a instrument grade shaft,and the right size bushings and regular grfite grease or marine grease.
If one thinks that alot of friction is present than he is flying Airplanes or Helicopters where power loss is a factor,in Subs this sizethat is a minimal consideration since the props are usually geared down ,unfortunatly the Lafayette is not ,in other words the amount of power loss is so minimal in ageared down drive that it makes no dent in the run time.
If the Lafayette had at least a 3 to one reduction gearbox the runtime would be much longer and even the motor would run cooler.

If I where you check to see if there is a bushing in the motor mount's shaft right behind the simitars seals seat area if there is none than the seal will only fail again and again no mater how much grease is used becuse these seals must have a support bushing to prevent shaft woble and rubber seals do not make good shaft supports.
They are designed to have it bushed that way in Automotive applications and Marine though not comon and I can see why not very reliable.
Sometimes the oldest simplest way just works the best and why redisigne it if it works.
BTW I never had to add grease to any of my stuffing boxes and they number in 30s.
Also I can personaly garranty that if made correctly the shaft will not leak,can Engel do that?

Dave Amur Sub Yard