Has anyone ever heard of creating a bypass of the heater by using a "T" and both rear water outlets on the heads. I'm probably not being clear...but I am experiencing 220+ heating problems and have done everything mentioned in these posts including replacing the head gaskets in case they were blocking flow. I only have 4,400 miles on a newly rebuilt 69 400 block and 72 4X heads. I have got the highest flow water pump from Summit, High flow thermo, 11" pusher fan, 7 blade fan with thermo clutch and shroud, desert cooler radiator, upper and lower baffles, .025" clearance on my divider plate, and ALL parts are brand new. I can go about 15 miles at low speeds (40 and under) before 220 and about 5 miles at 70+mph. I hate to belabor this subject BUT this can't be what was designed in 1968! HELP!!!