I understood the your post, $40,000 = about 700 man hours in a shop, no parts or materials.

Extensive rust repair on a 50 + year old convertible uibody that has little to no parts availability.

my experience says complete rotisserie overhaul and the media blaster will not be friendly.

This is one of those cars that you need to have 5 to 10K paid ahead of the bill to work on it so when the owner bails on the project your not left holding costs and a car no one wants to finish.