767Jockey Doug, the setup you have will be fine. Like others here on the forum a return line will extend the life of your fuel pump or pumps. From racing I can tell you that running an FI system with a return line from the front of the car does raise the fuel temp. Some of the heat comes from the track surface in the daytime, some comes from the resistance of the fuel lines and the pressure pushing the fuel through the system. With the amount of heat under a cobra hood, any line that can help insolate the heat from the fuel would be a help. I think the engineers at wherever added the turkey pan around the carb for a heat insolator because of high fuel temps and vaporlock and to add cooler air from outside the car. Your supply line size is fine. Cooler the gas the less problem of vapor lock you will have. I do open the hood after running to help remove added heat from the engine compartment. I would reccommend this to any one who has gone on a long cruise and stops for 10-15 minutes. This also helps stop the fuel in the carb bowls from boiling and the fuel pressure in the lines from increasing and pushing the floats open. This will cause a washing of the cylinders, black smoke and hard startup. Not good.
Rick L.