Try and get some pictures and post them here, especially of the frame around where the leaf springs mount, etc. Normal rust areas on a CJ are pretty much everywhere, but mainly the under the windshield, behind the front seats where the roll bar goes into the frame, floorboards, fenderwells, and behind the tail lights where mud gets kicked up and nobody hardly ever cleans it out.
The main problem with buying a CJ is that it always ends up turning into a money pit. Other than that, you can't go wrong.
1986 Jeep CJ7 4.2L I6 T176 (restoration in progress)
1961 Willys 4x4 Wagon L-226 I6 T90 (restoration also in progress)