Just a thought, but, it looks as though you have the cable running behind the head (obviously for nice clean looks) but, what about just running it straight over the top to the other side. A nice long gentle curve.
Gene - The issue with going over the valve cover is that the cable approaches the carb from the outboard side. I have the same carb as pictured below. (from a member of this site) Going over the top creates an even tighter curve.