I had a 240 wagon that the Ex-wife gave sold at 230,000 miles. It was begining to rust. The engine still didn't leak nor burn any oil. All that was in the engine bay was dust. We had a fuel pump go out on it after it was in storage the year I was in Korea. The speedo went out on it.
I then had a 240 sedan, with a 4 spd manual w/OD. I replaced the original clutch at 170,000 miles. The tranny seal had started leaking and oil was getting on the clutch plate. Went through another clutch pretty fast before I figured out what was causing it. I had to replace the engine wiring harness. It seems that's common on many Volvos over ten years old, and it's not that cheap. If the car cranks and cranks, and just doesn't want to start, or takes forever to start, it's the harness and they run like $700. I sold it with 193,000 miles.
I then had a 760 turbo. These were 4 cyl turbo charged, mine had an auto. Stay away from Pre-87 700 series automatics. The tranny in them sucks. 87 and later are strong boxes. If you put the car in Neutral and it creeps forward, the tranny is going. I had to do the wiring harness on this one as well. I drove the dogshit out of this car. I mean the living dogshit. I had actually no problems for nearly 300,000 miles. I donated it to the American Heart Assoc when the coil went out because I was ready for something different. I did fix alot of stuff, but nothing that you could say was due to anything by just getting worn out by use. The speedometer went out at 200,000. My rear suspension was an auto-self-levelling (nivimat) one, and that eventually broke at a quarter million miles or so. I swaped it for the rear spring set up of a 740. I had to replace the front struts about the same time. They were bowed out and rubbing on the inside of the tires. Remember this was at a quater million miles, and my struts would be bowed out too, so things like shocks, tires, etc you just have to replace if you drive a car 300,000 miles. Eventually small things started going bad. My A/C compresser seized up, my power seat stopped adjusting, my heater valve stopped working, etc. All stuff that basically wore out from use. The power windows and power sunroof never had any problems and the sunroof never leaked. The car really hauled ass because of the turbo, handled quite well, and got great gas mileage. It was probably the best car I've ever owned. Until the coil went out, the car started first turn of the key EVERY time.
The early turbos in the 240s sucked. They weren't intercooled and were similar to many early turbos in getting coked up and burned out. The 240's are rock solid because the engines don't really make any power, so there's never any problem with the engine running forever. If you get a 240, get a normal, non-turbo one.
The 740 and 760 turbo are really the same car. The 760T is just leather, etc. The 760 6 cyl is junk. In fact the 260 is even worse junk (which is why you never see them). They spun cams all the time. In fact Volvo had a repair kit that included a hole saw and a plug so you could cut through the firewall and replace the shaft without taking the engine out.
I liked the 940's though I never owned one, so I couldn't tell you what the problems were, same for the 850's.
I never had one problem with my engine nor the turbo in 300,000 miles. It was indeed leaking some oil by then, but it still wasn't burning any. I'd go with the turbo in the later cars. Mine was intercooled and the turbo itself was also water cooled, so it was far and away better technology than the 240s. The turbo is worth it for the performance difference.
They're well built cars, but like any car they need to be maintained properly to get those high miles out of them. Most Volvo owners are the type that take care of the routine manitenance, and when you do that, you can get alot of life out of almost any car. I wouldn't hesitate to buy another Volvo, but I'd damn sure have my Volvo mechaninc check it out first so I knew what I was dealing with.
I wouldn't bat an eye at buying one with the mileage you're talking about.