I do not see anything worrisome in the pictures, but I would plan on some extended preventive maintenance and care. The secondary fuel filters look as if they had not been touched in a long time...consider tossing them and the primary for a more modern spin-on setup (read up in the forum). The coolant hoses look swollen and perhaps leaky (last pic it looks as if there was a cut on the hose) - these and the rad hoses should be replaced. Might as well flush the cooling system while you have it open.
Leak-wise, the oil leak at the rear of the engine does indeed look like a valve cover leak. You will want to pop the valve coves off, toss the old gaskets and check (and set, when necessary) valve clearance on a new-to-you engine. The gaskets are thick rubber and do not like overtorqued valve cover bolts.
Good luck with your purchase!
