3208's @ 375HP

Hatt and other mfg's had easy to drop arches, mast and other high items that would drop to make that (#$%%^&*^ing) Chicago bridge. Some of these were rather long in LOA.
There out there, your just finding the wrong stuff lately.

If you are going to keep the boat awhile and put lots of hours on the engines, yes new power may be a great plan to ensure less troubled time down the river.
Rebuilding a later engine may be an idea also. Sadly, you have not mentioned any later engines.

Recovering those funds may / mat-not be realized on your re-sell.
The recreational boat market has been a wild ride these last few years. I expect the same for the next few years.
Remember, it is recreational money, like going to a movie... It is not an investment.

The 3208 engines were good engines. Otherwise they wouldn't have been able to sell them for so long. The market agreed that they were good. Did builders put too much or too little engine in a boat? Possibly. Did some owners run the engines hard and neglect maintenance? Possibly. Did some owners run them gently and obsessively maintain them, even if they were high horsepower versions in trawlers that previously had smaller engines? Possibly.

The power choice in a new build may not be of science, engineering or dependability but rather what meets the needs of the hull and cost the hull mfg the lea$t.
Cat makes a heck of a lot of engines. They warehouse them sky high all over the world.
Your a boat builder? 100 engines can be on your door step in a few days.
Back many years (and more), Other than Detroit, what else was competing against the 32xx's? Maybe some Cummins V8s?

So, IMO, it was not the power choice of the consumer, just the economical choice for the boat mfg.

Cat is not and has not built 31 or 32XX engines in a while and parts are getting scarce.

It follows reason when you start with a 150HP engine and start pulling 375 and 450HP from it, life expediency is suddenly shortened.
Cat did make some mods the the later HP blocks (oil galleys), but it was still a poker hand; sometimes you got lucky,,, for a lil longer.

Then, years (years) later, used boat shoppers come along looking at used boats with these old engines. Some puke has changed the oil and spray painted the engine (aerosol overhaul) and their still running. That EOL poker hand has not been called yet.
The drop out used car sales person promises great adventures.
Does that boat shopper really want to play somebody else's poker hand? With near everything against him (her)?

Detroit's have these same limitations. I've just been tinkering on them since I was a kid. I luv the 71's, yet I still hate the 92's.

So my friend, I don't think the market agrees they were good, The market learned to live with them.
As I have learned to live with my 71s.
As most learned that what ever brand daddy's car was, was good also.

The 8.3 was a favorite even before that high pressure pump (Common rail). I don't think there is a more bomb proof engine than the 450HP QSC line.
Of interest; Max HP was 650 but emissions restricted that back to 600HP, not because of any engine problems.

I don't think there are any valve dropping comments around here on the Cummins 8.3.
I can tell you all about Yanmar and Cats dropping valves.

The 480CE was sort of a Diamond-series 450C (6CTA) with added electronic controls of some sort.

I thought the lowest/original horsepower for the Quantum Series (QSC; is it still labelled 6CTA?) was 500... with 550 and 600-hp versions eventually appearing too. Seems to be one or both of the latter maybe had a higher WOT rating, i.e., higher than 2600.

We had 6CTA 8.3s in our previous boat... which was built just before Cummins introduced the QSCs. Our 450Cs seemed good, no issues. At the time, 480CEs were available, too, I guess as an option. I always thought QSC 500s would have been the cat's meow. Note sure a 550 or a 600 would have been worth any extra for that hull.

-Chris