Header to trans. line and shifter cable clearance

If increasing clearance isn't possible, then you can buy insulating material (e.g header wrap, spark plug wire insulation, etc.) for either header tube or the cooler lines/cable. The volume of fluid traveling through the cooler lines won't significantly heat up through brief exposure to a hot spot. I think a greater concern would be if you somehow developed a cooler line leak that close to the header tube. I would worry about the cable getting damaged, or melting, close to a header tube.