Since you've already have knowledge of what you need for overlanding equipment. Here are H3 specific items.
1. CV axle, I always carried 2, I had a bad habit. AC Delco preferred.
2. Upgrade the tie rods to 16mm or Outfitter Design HD kit.
3. Upgrade the steering rack clamp. OD and a few other options out there.
4. Upgrade T case shift fork to metal.
5. 35"s, mild crank on the torsion bars is all that is needed.
These will get you over the hump and most other items will be age related wear items with little to no upgrade. H3 is an old platform and some parts are getting harder to find.