My '67 gto 400ci (rebuilt 8k miles ago w/roller cam etc etc) wants to run near 230+ degrees. I've tried a new shroud, a 7 blade fan, then an electric fan so I guess my next step is a better radiator (still running stock radiator). Can anyone recommend a great radiator? I'm told a 4 core aluminum is best but I'm not sure what aluminum does that others (ie copper) don't. My goal is to drive it on the freeway in the heat of Tennessee during the summer and not have to stare at my temp gauge. Any help/advice is much appreciated.