Richard & Ray, stop (or my head won't fit through doors).
We run into RE-sale issues a lot. You know the drill, the seller wants to make it look as good as possible so he can get the most money for it... I'm not saying everyone does this (but they all do on eBay). 'Honesty' is a scarce commodity that quickly turns into, 'buyer beware' or Caveat emptor.
I would want to see coolant that's NOT new, and oil that's not freshly changed. Yes, oil changes come due, but then operation continues which usually makes oil look new-ish. Same goes for coolant. If it's fresh green and you're pulling scum off the bottom, you know the block and other parts are in the same boat. What's more, it probably didn't go through many heat cycles to break up the oil.
So I would be suspicious. You want it to last years. Start the engine and let it warm enough to open the thermostat. Try to run it under a good load and listen for any rod knock or piston slap. Look at the blowby and the exhaust color.
I wouldn't expect it to run 'tight' because it is older and worn. The timing chain is probably somewhat stretched, causing an acceleration lag from a stop, and irratic spark timing. If compression is low on all cylinders, it will still idle smoothly. But if compression is low on a few, it will never idle smoothly. Let your test drive tell the story on fresh gas. If the truck has old gas, don't attempt to start it. You can smell old, nasty, gas.
Hope this helps. - Dave