RUST!
I was able to get a couple of good shots of the worst rust on the car… at least, SO FAR this is the worst rust detected. The following photos show the ends of the rocker panel where they meet the rear wheel well. I suspect this area is so rusty because water is able to run down into this area from where the convertible top edge meets the rear window frame. It looks pretty nasty! It should serve as an opportunity to test my metal fabrication skills.
I have been repairing a friends 1960 Electra hardtop and the rust is similar. On my friends car there wasn’t anything left to copy so I used your pics to get some idea of what the missing bits should look like .I put the rust down to the old style underseal drying out and letting moisture underneath .