Is it worth it?

Actually tops of fenders, wheel arches and under the rear fender chrome strips are extremely common rust areas on 65/66 cars.

Unfortunately so is the inner cowl vent areas and that is a crazy ***** to repair.

Another area is the rocker panels.

Check those before making a decision. I like to open the vents in the passenger compartment and put as much of my arm up in there as I can. You should be able to feel the top of the opening and around the base. Rust holes should be pretty obvious.

Laysons (member and vendor) used to offer rear patch panels. Pretty much the only source.