If the milage where true could be a real good parts car. Seldom is though. The more time I have in with older diesel mercedes the more suspicious I become.
Even the ones I think might have accurate odometers still leave me Wondering. In the car world it is a well known fact you cannot put miles back into a car.
Might be possible with excesss spending but even then it is not the same. I really believe there is not another brand of car out there with more odometer problems and manipulation in general than the 123 series has experienced.
Nice to see the liquid crystal type of odometers in later years on other models. . Even these are changeable. Fortunatly the device to do it has been expensive and the risk greater if the new owner finds out. Hopefully this has slowed down the practice somewhat. Just do not count on it.
Check out any expensive cars background carefully before handing money over. I still have no clear picture of expected lifespan of the average 300d engine. All I suspect is it might be pretty high.