302 Reverse Rotation Rear Seal

Hey Guys, New to the Forum and CCs.
I recently purchased a 1980 Tique in remarkable condition, previous owner was up front about the "common" rear seal leak that the 302 seems to have, it just seems to be a bit more than I was expecting. I am typically going through a quart about every 3 hours of run time at an average of 20-25 MPH cruising speed. again, to me, this seems like a lot, and I'm just wanting to know if this is considered normal for an engine that has roughly 100 hours on a ten year old rebuild, is there anything I can do to lessen this, like additives, or different oil, or am I just going to have to pull the motor and tear it down to replace the seal? The previous owner was running Valvoline standard 10W40, I have only had the boat a few weeks and have continued with that oil so far, while getting to know the boat. I have read a fair amount of debate about the different oils and was planning to make a decision on the new oil I would run as I got closer to my first oil change.
FYI, I do have a catch pan under the rear seal with oil diapers in it, so I am not creating an ecological disaster.

Sorry the post is a bit long, just wanted to get the relevant info in up front.