I would not purchase a 1987 300TD with a rough body and 300K on the clock, even if it was sold to me at $500.00.

Vehicles of that model and vintage require significant investment of knowledge and parts........to the tune of $2K per year........if you intend to stay ahead of the repair curve. Now you have a decent vehicle with a rough body. Additionally, an engine with 300K is no bargain. There are no assurances once you get over that number. Sure, there are folks on this forum with close to 400K, but, what's the odds that you will have the same result?

Find a better example, or consider a lower cost M/B such as the W123 series where parts are less costly.