At stock power levels, I'd not worry. If it runs it runs. The thing is, you have to wonder when injectors, hpop, and other stuff was done. I personally wouldn't give a crap.knowing what I've done to mine in th 265k I've had it, I'm amazed it runs. At all!
Knowing what you know, if you can look at one and its got 300+ I'd negotiate a set of stg1 sticks into the true cost of buying it. Also hpop, hpo lines, glowplugs, gp relay. A fuel system probably would be wise too as the old lines, fittings, and pump are degrading. It's my the motor that is the issue it's EVERYTHING else. You would need good receipts negotiate a deal. Also, things like brake components could be at the end of their service life.