ok, been exploring the overheating again, I currently running 350 engine, rebuilt, new 3 core rad, new water pump, just installed filler plates on top between core support and grill, was using stock (new) fan clutch, with bigger fan, and now trying a plastic HP fan, not working so well, driving my temps stay around 180, stop light to stop light, or parked temp start rising up past 200, with original fan clutch i raise the rpms up and the temps start to drop. I was reading in here that maybe I need to scrap the headers and go to HP manifolds, anyone done this? and I was looking into changing the shroud, mine is 6" deep and I seen a 9" deep one for 400 models, that would eliminate the use of a spacer on fan.