Disclaimer...I own a 48LRC so of course am biased
Mako you make some good points Having owned 2 Hatteras boats (currently a 48 LRC) I will offer a different perspective. They can deliver a lot of value. The OP owned a 53 Hatteras so is very familiar with the brand and the systems.
For sure don't buy any boat with a full survey and a healthy budget for repairs and upgrades. Mako points out some areas to focus on.
The good news about a 50 year old boat is that if it has been active and even reasonably cared for many of the original systems have been replaced and/or rebuilt. On a Hatteras as on most boats, and assuming no structural issues the big ticket items are mains and genset, paint, stabilizers and Air conditioning. Not to say you wouldn't find more things to spend money on but they are generally not as expensive. Also the old boats don't have $5k ECMs that while delivering performance and efficiency are black boxes requiring a tech specialist. I have made my career in tech so not afraid of it but now there are so many sensors and electronics in engines a simple item can hold you up. I am sure we have all seen this on many of the YouTube channels. I have watched (with some pain) the issues with a brand new build on this channel.
A few positives about Hatteras is no teak decks and they have fiberglass tanks. Old tanks made of anything else are ticking. The replacement can be very expensive as many boats seem to be built around the tanks. For the particular boat in question I would see the mains and the air conditioners as potential near term needs. If the ACs are 10 years or newer that would be a big plus.
At the offered price and assuming the big ticket items are in good condition it seems to be a fair price.
The 48LRC is essentially the same as a comparable Nordhavn in terms of capability. That would run you $400k-800k.
Almost all boats of that generation have some blisters but at least in my experience it was nothing structural and just an item to keep up on at haulouts.
Wet core can be present and identified at survey. But a pretty easy fix if found and not crazy money.
In conclusion if a buyer wants a really well built "small ship" and cannot afford (or just choses not to spend on) some alternatives that are well north of $500k then an older boat such as this can be a reasonable alternative. I don't know if any of us knew (at time of purchase) or perhaps even now know what a boat will sell for in 5 years. If my funds were unlimited then I would buy a new Flemming. Sadly that's not the case but I can do a lot of the same experiences on my 50 year old Hatteras 48LRC.
As another alternative, Michael, the OP could find a newer boat in that $180k range. But not many I know of will have the ruggedness, space and features of the one he is considering.
Ken