Spare parts
jibes,
As I recall you have an M25. A friend of mine recently purchased a used M25 with 1,037 hours on it on eBay - I don't know the cost, but all he had to replace was the front bearing case and add a few other minor things like a glow plug solenoid and an oil pressure sensor and he has it running. He bought it to replace an aging A4 in his 1974 Pearson 10M.
While I don't know his raw cost for sure, YOUR stated cost for "spare parts" for your engine seems to me to be
WAY over the limit.
Here's why: Our new 3 inch HX was $300 in 2001, can't be too much more today.The exhaust riser from Catalina was $185 in 2003. I get alternators from our resource in Wisconsin, 100 A high output with plug & play harness connection for $160 including shipping. So how come that's way less than $1K for the really expensive parts?
So, without a detailed accounting, or maybe with one (!

!): How'd you ever
"...get to about three to four grand...???
It is unfortunate that you have already purchased these items, as it seems from your post. Next time you're shopping, give me a yell, first, and I'll try to guide you into finding some better priced resources for you. Torresen usually does have all the parts and they are great for those parts that are unique to Universal engines, but they aren't the only kid on the block when it comes to engine parts. For instance, Sen-Dure does the HXs, although I bought mine at a local Universal dealer here rather than buying it from afar (that was a long time ago, too, way before online shopping became so prevalent). Oberdorfer pumps and parts can be found at discount, whereas Sherwood pumps and parts never can be discounted. If I had a Sherwood raw water pump, I'd replace it with an Oberdorfer (which is what we do have).
The question is how many engine hours you have. Me: 2333. A friend, before he had to replace his M25XP with an M25XPA was well over 5555+. This friend is one of our mechanical gurus. He would keep anything running and be able to fix anything. He got tired of dealing with seals issues, and he knew he would keep this boat until they tore it out of his clenched fists, so replacement was a no brainer for him. His replacement story is in the Nov. 2009 Mainsheet magazine (unfortunately both horribly and heavily edited). We'll have the full story with color photos up on our Tech Notes Online very soon.
I'm guessing you have lotsa life left in your old 3 banger!
Most responses to the basic "Is it worth re-powering my boat?" usually ends up with: "Only if you intend to keep her for a long time." 'cuz you'll never get the $$ out of it if the boat sells soon afterward.
If the only reason you have to consider it is "
...is worth it to end up with a 24 year old motor with a few new parts?" then engine hours, general condition, and how it's been treating you over your period of ownership (reliability), come into play.
One of our C34 skippers, with his new-to-him 1988 boat when he first bought it maybe five years ago, went through the same thought process, and mentioned the Beta, too. He thought about it some more, listened to our input, then shopped and purchased parts frugally, and still has his now trusty M25XP purring right along with almost 2,000 hours. This same skipper wrote this article on our C34 Tech wiki:
http://www.c34.org/wiki/index.php?title=Rebuilding_the_M25-XP I don't know what that cost, but it sure had to be way less expensive than a replacement, right?
Our engine is now 22 years old. Still going strong. Just getting warmed up. You get the picture...
Knowing you, I'm sure your engine is in perfect condition and well maintained. The conclusion then becomes much clearer.