i started by handing sanding. That was a terrible idea so i invested in a electric sander. Much easier still time consuming. Nothing like sniffing 40 year old paint and rust in the morning.
Nice... I wish my fenders were salvagable... but they welded metal OVER the bolts into the rockers on the bottom, so they get a bit of damage when getting pulled off. Also, they did a poor job of the welding and bondo... so the rust just makes it not worth it, if still possble.
My uncle took good care of the body for the most part aside from it sitting and collecting rust on the hood. Interior was gross so i tore it all out. When he parked it it was at an angle or got a flat cause the rust on the passenger side is way worse than the drivers. Both passenger floor pans need replacing but the drivers side has minimal rust.
Do yourself a favor and get some paint stripper. spray on. let it do its thing and wipe off, and some finish sading. Less stress on the metal and a lot less hours spent.