Freaked Out By Roof Rust

Going to check a couple of salvage yards in the next few days. I was told about the possibility of a Dart sitting in one of those yards. What model years could be a direct swap if I was going to swap out the roof skins (and other parts...fenders, quarters, etc.)? I have a buddy who is expert with a welder who is committed to helping me swap the top if I can find a good roof.