I am considering buying the patch panel from LMC (or similar), and removing the spot welds from the pillars, and along the section the supports the window. BUT, the center section of the section that supports the window is also missing (as in rusted away). Drivers side is the same way, I don't have a picture of it on my computer. Not sure about how best to repair the window section, again, considering putting the support in first, and then making the patch for the roof/windows. It looks as though the windshield pillars were replaced at some point, there is some "lead" filler visible on the left hand side of the photo. Top and bottom of the pillar. Drivers and passenger.
Welcome to the forums. Lots of help available here on Stovebolt.
That lead you're seeing is from the factory. That was used back in the day instead of fiberglass filler.
Your cab doesn't look that bad. There are a lot of posts with advice over on the paint and body forum.
Good luck with your project.