Hatteras 48 CPMY and 52 CPMY - seeking suggestions & info

That included the yard, heavy work and what else?

Sadly, no surveyor has a crystal ball.
They can report as to what they find and based on their experience or support from people in the know, offer you a condition on that date.
So you want the best DD guy you can find. Sadly, these guys are getting far and few between.
Another reason receipts and records are a must. Oil labs getting tracked. Injectors under a watchful eye.
It is important to know if the engine was repaired for an overheating issue.
Any 92 that has been overheated, walk,,, run away from...
Any 92 that has had coolant or any water in the lungs, Run away from.

TAs have two heat exchangers, good to know if they have been serviced.
TAs have an internal air cooler (After Cooler). You can not see, access or test it. Records show its last service or replacement.

So, a stack of records, An old bearded DDC guy (still alive or at least not blind) and liner inspections.
As I mentioned, a good engine survey could take days and the tech is working, not on a boat ride.
If a kid shows up, fire him and re-read this post.

My starboard 12v92 was over $100k to rebuild (yes, one engine only) but that is extreme. Tore the thing down to a bare block and replaced everything except block and crank - liners, pistons, rods, heads, blowers, turbos, coolers, every hose, every clamp, etc. It was basically a new engine. And I had to replace one exhaust manifold that was like $8k just for the part.

One exhaust manifold? That is one, 3 port log? Same manifold that fits a 6V92TA?

No, the whole 12 port manifold in two pieces. Very hard to find.

sorry, meant 6 port manifold.

If you must shop for an old Hatteras with Detroits, Look for the series 71 engines.
Way more forgiving, less temperamental.

Two, manifolds per side. 3 ports each.

After reading all this really makes me appreciate my old hopped up low profile J-T 471ti engines 1980, with the M95 injectors (M15). Not sure of the HP they make , but from searching around the web, 325 to 35o HP . (I did find out the J-T was calling them a "CAT killer" (3208) and were trying to get more of the smaller engine market back in 1980s .) I do not push them and I service them myself all the time. All I can say is they are fine running engines, but as to the posts here they are really maxed out yet run fine as wine. I dunno.....Lucky perhaps?

Hours unknow...meter was broke when I bought the boat at 1689hrs. Did a good sea trial on the boat before I did the deal.
All this being said both are running fine. I mostly run them between 1500-2000 rpm. depending on my time , weather conditions and how much fuel I'm in the mood to burn up!
I've put on around 900 hrs on them.
BUT I knew when I bought the boat 71series parts are easy to get and I can afford them. And I know of various DD mechanics around so I took a chance. Also bought the boat at a low price.

I think the point was made, rebuilding a boat engine is expensive.
Additional thought, rebuilding any boat engine is expensive.

The point I was hoping to make, high HP extracted from a small package shortens its life.

Survey all engines very well.

Demand all history. No receipts and logs, didn't happen.
Boats are not cheap. Boat owners can be.
Nothing worse than a cheap & fibbing boat owner but a few are around.