Stainless;
I had a similar problem when I built my chassis. The roll cage front hoop needed to be bent to follow the profile of the rear edge of the windshield. This was a large, non-constant radius bend. I took two lengths of tubing to an off-road 4x4 fab shop and explained how I thought the bends could be made- make a slight bend, move the tubing forward a bit, and make another slight bend, etc. It worked out just fine and the second length of tubing wasn't needed after all. I made a Masonite template of the inside of the windshield curve and the bender operator followed that curve. It worked out nicely. Maybe you could try the same trick?
Regards, Neil Tucson, AZ