Hi Matt. Was nice speaking with you this evening. It sounds like you have done your homework. Key points to recap:
1. Get them to include a spare tire, even if not a match, something is better than nothing if in need.
2. Have them dump the fuel and refill with fresh diesel if you said it does not seem right. Same with the fuel filter(s). Then take it for the fast drive and make sure engine power does not taper off until 2100rpm (approaching governor limit). Half tank refill is much less cost than a heavy equipment tow bill.
3. PCB can be rebuilt with new solenoids which easily available. If they do not include the second PCB, not a big deal, you can give in on that one. Just buy the solenoids and rebuild yours one evening, and done.
4. Be conscious of any blow-by out the draft tube. The 8.3L should be a clean runner. Could mean cracked rings from extended sitting then start. If blow-by is visible and smells like burned motor oil, then avoid it. If a slight amount of visible vapor, try to gauge if it is coming out as puffs (a cylinder) or as a steady stream (possible condensation in oil).
5. Trans should shift smooth, like a school bus, up and down. Harsh downshift, especially 2-1, is likely sticky kickdown cable, spray lube down it at the engine throttle connection, work it in by snapping it a few times and let it return, and drive it again.
Good luck, come back with stories.