You do not say what area you are in.
West coast Zuk's seem to run lower in price, and usually not have as much rust problems.
4 door Track/Kick's are close to 11" longer wheelbase, so turning diameter is slightly bigger. Usually that longer wheelbase works in your favor, especially in going down steep hills with even small steps (which gets critical in a 2 door).
56K on a 1989 would be extremely low miles, and more than likely the odometer has turned over.
Aluminum patched rust holes is just covering the rust area. (Aluminum won't weld to steel, so it is sealed and screwed to cover , not replacing the rusted area.)
Having a mini spool installed would probably be close to $300-$500.
90% tires means they have a lot of mileage left. For off road and extreme back road travel Mud & Snow have more aggressive patterns.
4 door zuki's do have more room inside for gear, passengers, dogs, meat.
Good Luck in finding a good hunting rig.