Good find! Nice condition for the age. I wouldn't worry about modifying the design. It looks well built for areas out of the path of a hurricane. Clean it up and enjoy C-band. Agree, the buttonhook design will sure simplify FD setting!
Mesh overlap will not be an issue at 3.7-4.2Ghz and was very common in many dish models during the early 80's. Take a few pairs of gloves. The mesh edges will eat gloves like bonbons! Hope you are up to date on your tetanus shot!
The design of the dish is a series of semi flat panels and not forming a true parabola. The design will be less efficient than a formed / shaped surface, exhibit a higher noise level with slightly increased sidelobes. I am sure that C-band performance will be fine, but KU will likely not be very good. The dish was probably distributed long before KU reception was common.
I was out looking at the dish panels yesterday and discovered something that I hadn't noticed before. The cross braces between the ribs are curved.Since the mesh pop-rivets to the braces as well as the ribs...it bows the mesh into a more parabolic shape.So the panels are not flat after all.
The old mesh needs a good deal of tightening up before it gets mounted. I might re-mesh it with some KU capable mesh instead...if I can find something cost effective.
If not the whole dish, then as much of the center as possible....keeping the original (Large hole) mesh on the outside.