I'll just comment on the rear end photos.
When the rust is showing on the outer panel under the tailgate then the rear body (not chassis) cross member has gone. This member supports the back body and the curved section of the rear wings. They can be purchased at around $800 (+shipping, duty and vat) and they are welded in. I made mine (see evolution of my 40 in the archive).
The rear lights should be recessed into the rear chassis cross member and it looks to me like the has been skinned thus telling me that the outer rear chassis legs have rotted. The lights fitted are not 40 series.
All these problems are caused by mud being left at the back inside the rear arch and under neath.
It can be done (mine was worse as the wings had started to go too) but it depends on your skills - metal shaping, welding, etc.
IMO this one has not been looked after that well but it is probably around 40 years old and it is recoverable with work although expensive if you have a professional do it.
Hope that helps
Regards,
Rodger