Looking good Bob.
Your pics bring back memories of restoring my 12 cab...
I like how you made the bottom framework for the cab.
I made my pieces from flatstock cut out on the bandsaw to the correct radius and pieced into place by cutting out the bottom part of the angle and then wrapping the angle to match the flat radiused piece.
No fancy bending required and just a bit of welding. Of course I had made a template on a sheet of plywood just to be sure using the old frame.
At the end of the day whatever works.
Just wait until you have to re skin the back of the cab.
My windshield frame was custom built from 2 M37 window frames, cut and welded on a jig to original specs using the old refurbished hardware.