340 overheating problem

Has this current setup run cool before and this is something new, or has it been like this from the git go? The fact that at idle, low speeds, and highway are all the same, tells me it's not the fan position causing it.

Any chance your running ignition timing that's on the low/retarded side? That can in some instances cause issues, but still, at highway speeds, there should be plenty of advance to not run somewhat hot.

Your setup looks nice.....i'll think on it some more for now.