Can you send a pic of the entire panel and the spot? The bottom is a little rusty as well. Are you sure the bottom and wheel wells are solid. The shot you gave us has a lot of surface rust.
If you heat that panel you will probably expand the steel too much. I would do a through look at the inside quarter at trunk, qtr window and inside wheel well. These qtr panels rust out with humidity. Where has the car been the last 40 years? It may look good because it was patched.
Engine Test Stand Playlist: https://www.youtube.com/playlist?list=PLwoxyUwptUcdqEb-o2ArqyiUaHW0G_C88 restoring my 1968 Firebird 400 HO convertible (Firedawg) 1965 Pontiac Catalina Safari Wagon 389 TriPower (Catwagon) 1999 JD AWS LX Lawn tractor 17hp (my daily driver) 2006 Sequoia 2017 Murano (wife's car) 202? Electric car 203? 68 Firebird /w electric engine 2007 Bayliner 175 runabout /w 3.0L Mercuiser__________________________________________________________
