I have the same-85 4runner efi.  Goes pretty much everywhere as is with street tires.  All I have done so far is straight piped the cat and a cone filter to replace the air box.  My other rigs are way more built than this.  I would suggest maybe a locker for the rear and some decent tires and go have fun.  Maybe a shackle lift or body lift-or both-they're real cheap.  You'll find more parts and mods you'll want to make as time moves on.  Good luck!