When I converted to Electric Propulsion I sold my dead Westerbeke 27 engine to a fellow who purchased the same model boat that had sunk and he was bringing back to life. Sold the engine for $500 and transmission for $700. He did the rebuild himself spent $3,500 in parts and ran it for two years and then he replaced it.
Not identical of course, but similar experience for us last year. I gave away a decent-running Universal 23 hp diesel engine complete. I shopped it around a little and could get $1K for it, but thought it over and just gave to a friend who is rebuilding it to repower an older boat with a long-in-the-tooth Universal two cylinder engine.
In my situation, the panel had no value and the harness was overdue for replacement, the engine had quite a bit of blow-by, and with 2200 hours the original Hurth 50 trans was a huge question mark.
Our new Beta 25 was almost $10K with larger panel and upgrade alternator.
Everyone has a different calculation for making this work.
I talked to several experienced diesel mechanics and decided that IF I took out the original drivetrain and rebuilt and replaced everything that needed work, I would be out 5 or 6K, and still have an "old" engine.
The new Beta is SO much more quiet and the vibration is much less! I repeat: it's Quiet.
Obviously we are in this for the 'long haul' so we do expect to amortize out the expense in reliability at the least. I also figure that the Beta is a good gamble because our moorage has quite a large number of similar engine replacements in the last ten years.
(There have been some other brands installed that proved to be a lot less reliable, but that's a subject for a different thread. Experienced wrench turners can likely guess what those are......)