This may or may not be relevant to this topic....but a data point nonetheless.
I took the original exhaust “bending card” to a local shop for my 1951 half ton so I could assemble at home.
We could NOT get the header pipe to line up correctly with the manifold. Finally just gave up trying to make it work and took them what remained of the old rusty header pipe to duplicate the angle.
My truck has a later 235. My theory was there must be some subtle difference in the outlet angle of the manifold. But I believe a 1951 216 (which should have been the template for the bending card) should have had an angled outlet, anyway.
