If at all possible, get underneath the car. Rust in Wisconsin is as bad as it is in Michigan, I'm sure. Floors, both interior and trunk, the bottom of the 1/4's and fenders, the wheelhouses, around the windshield and backglass, dimples under the vinyl top if it has one, hatchet jobs on any of the wiring, mis-aligned subframes from old collision damage, poor fitting doors, mis-aligned sheetmetal and a thousand other items that space prevents listing.
Just use the perverbial microscope. Maybe you found a good one. Good luck to you.