I would rebuild the 78 2f, pull the body, but keep interior and swap the 73 body onto it. All the good stuff from the 78 plus the heavier duty body from the 73. Get an oem style soft top. Boom.
I think you have made a wise decision assuming your primary goal is to have a restored 40 in the end. Of course restored means different things to different people.I think I have decided to pass at this point. He isn't coming to the price I was looking for, so I'm taking it as a sign. I was kind of locked at the $5000 due to the amount of work going to involved. I think we will wait a few years to look for one a little more expensive and less of a project.