By your description, your body is in very bad shape. There are still bodies out there for sale, but most likely they have rust issues as well. At least you have a known body. You know it is rusty as heck and need to have it fixed. The difference between a slightly rusted body and an extremely rusted body can be several thousand dollars in difference of restoring them. You need to decide just how much you like your car before making a decision to get another body.