What to do? That's easy. Get it driveable, then drive it. Enjoy it first, then set your long term goals and budget for it. You may find that driving it changes what you really want to do. You may decide to keep it very stock, or you may decide to go wild. In the end, it will be far cheaper to buy a "wheeler" if a wheeler is what you want. On the other hand, many people enjoy building a truck and fiddling with it for years, and they don't have a lump sum up front to buy a "finished" truck.
Here's what I would do: Find a 76 or later axle for the front to get disks. It's a one banana job and they aren't that difficult to find. Once the brakes work well, just make sure the cooling system is in good shape and other hydraulics (clutch slave). These are all relatively "cheap" items and easy to fix.
Forget power steering for now...just do skinny tires like I run and it's not too bad with no power. Forget the transfer case for now, it should be dead solid as a road driver before you take it on the trails. Trails have a way of surfacing any weakness at the worst time. So......all that gives you time to enjoy it with little money invested and little effort. Well, the electrical may take some time, but I can offer advice. Find every ground connection and CLEAN IT!