The real question is, "What do you want to do with it?" If you'd just like to go camping or fishing it in once in a while, just clean it as noted above, check the tires and brakes, and take it on a test run. Fix the broken stuff, wash, rinse, repeat.
If you want to resto-mod it to be your pride and joy, then get ready to open your wallet and/or roll up your sleeves.
If you want to sell it, just clean out the junk and market it as "original."
"Between what matters and what seems to matter, how should the world we know judge wisely?" - E.C. Bentley, Trent's Last Case