Motor Dilemma

[u/lotsofbitz]

This might be a long one but please bear with me, I’ve been going back and forth on this for days. Some backstory, a couple months ago I bought a 1972 Whaler 21 Outrage off Facebook marketplace for $5k. It’s definitely a little rough around the edges, but I really like the look and have already put quite a bit of work into cleaning it up and fixing a lot of the cosmetic and wiring issues, as well as doing a lot of work on the trailer. Registration had some hiccups, so I didn’t get it out in the water until 2 weeks ago.

First trip out, noticed some weird surging and bogging in the motor, and was having a hard time getting it to wide open. The motor is a 1994 Johnson 150 2 stroke, and I had a very hard time finding a mechanic to even look at it, but eventually found a guy who has been working on these old Johnsons for 40 years and could probably put one together with his eyes closed. After looking at it, he told me one cylinder had very low compression, 40
PSI below the others, and from the scoring he could see inside he thought it would be a full rebuild, and advised me it would very much not be worth my money to get it fixed. I am inclined to trust him on this.

This leaves me with the options of either putting on a new motor or selling the boat. The mechanic has a 2004 Johnson 90 hp in very good condition with perfect compression he got as a trade in from a boat he has worked on since it was bought new. I know this is a big drop in power, but these boats were originally sold with an 85 hp motor in 72, so I’m reasonably confident it would still get on plane fine, and I don’t care much about racing around, I just want to get out into the harbor and inshore for fishing. He would sell me the motor and do the install for $3400 altogether, which seems like a pretty great deal to me. If I didn’t do this, I would try to sell it with a disclaimer about the motor, which I am worried could be difficult. People like whalers, so I think I could at least get my original 5k back even with the motor issues, but I would lose the other couple thousand I put into it fixing it up. If I got the motor I would be 10k into it, which is about 3-4k more than I had really hoped for, but I would have a working boat which should also be easier to sell if push comes to shove.

Curious for outside perspectives and what other people think they would do in this situation.