the 78 is prolly the keeper.
pop top and fuel injection. assuming the original running gear is all intact.
I'm not sure what you are hoping for as a tow vehicle.
you might should go drive one before you decide you want to build one.
they are kinda funky to drive and underpowered.
slow but steady...
all of the body panels are available re-popped. and steel is the only way to approach it seriously.
and all of them are rusty.
some rust is more devastating than others.
you can send me a pic if you don't want to post one, and I can advise you better after viewing it...