I had a 240, before they could be called classics. Drove it up to about 320k miles before the odometer broke but it was still going strong. I wanted to sell it and get something more modern, because even though the engine was great, the car was aging around it - rust, no A/C, glove box door flopping open over every bump, suspension bushings clunking, etc. It added up. At that time it was just an old tired car and no one wanted to buy it, esp. because of the unknown miles. So I ended up selling it for $700 to a Volvo shop for parts. I said “can’t you give me a little more? The engine runs perfectly.” The guy said “yeah, they all do”.

Point is - if your engine happens to be shot for some reason (like lack of maintenance) don’t spend big money to rebuild it, because there should be tons of good used ones available that should drop right in.