That is a great deal. The engine alone is worth the asking price.
I would not hesitate to buy (also cavitation is a huge issue in the older fords with the 7.3, not in a 5.9 cummins) Expect to replace a few parts though. Probably start with front calipers and brake lines. I suspect the brakes are soft because they need to be bled and the bleed valve was corroded and broke off. Calipers are cheap and easy, you can do both fronts for under $100, master cylinder is under $50. Good luck with it and be sure to check out turbodieselregister.com