Frank
Downfall of the 250 is the head and manifolds. Prone to cracking, especially on the front corner, that's why the specs for torquing the head was changed for the one bolt. I've ran a few of the 250's, most went over 150,000 miles with one head rebuild, and little oil use. Usually the rest of the vehicle was worn out before the engine. I would get Leo Santucci's book on the Inline Chevy Six, it's a good reference on what to do and not to do. Available at amazon, B&N, and other places.
