Can these Fast backs be saved?

I have an old Mopar buddy from Tn. He calls them "quilt" cars!!! Any car that is not 100% from the factory steel is a quilt car!! He has more $ than most of us!!! But he has several 70 Hemi Cuda survivors.
I don't mind cutting and welding as long as the rust goes away!!
i never heard of a quilt car. up here in the great white north , when there is no frame or floor left we find a car with the same wheel base or about and cut it from the floors down and but the body/skin(pelt) onto it and the rest is welding it back up. Camaro's / firebird's fit nice under mid 30's to 40's bodies well. i can see a more door a-body Valiant/ scamp etc. sliced and it would fit nice under one of those cuda bodies as a good starting base for it come back to the streets or track in this case.