Let's give this a try. But remember, I'm not an engineer and I'm take measurements off an 80+ year old part that probably hit a tree or two within its lifetime. Let's start with the overall length end to end. The entire thing is 54 inches measured on the CL of each curve. The last inch is crushed in a half moon shape at both points, at the end of the tube and at the crush point where the mirror mounts. This flat area creates the hole point for the mirror post. It is not a flat crush straight across the tubing. Starting at the cab end anchor point. The first bend starts at 25.5 inches and carries through to 28 inches and is 60*, so center of the bend would be 26.75 inches. Second bend is on plane and starts at 42 inches and carries through to around 46.5 inches, so center of bend should be 44.125 inches and holds right at an 80* bend. The last bent is 90* on plane to the first two bends. it starts at 49 inches and carries through to around 51.5 inches and is an 80* bend. There is actually an additional slight bend in mine at around 33.125 inches but I think it might be an incident bend because it doesn't appear to be a smooth transitional bend, it's a little wonkie between the first bend and this slight bend. Material width is 3/4 inch pipe/tubing with a .125 wall thickness.
I had my math teacher wife read this and she was able to figure it out. So I hope this works for you. If not, let me know, and I'll try a different approach. I'll send you an address so you can mail me one to test out for you