Cooling issues

I ran a factory 26" radiator with the factory fan, shroud and water pump on my 440. I kept it at about 185 with a 180 stat in it. The radiator started leaking, so I went with a Champion 3 core aluminum and kept the factory fan and shroud, it keeps it about 180 most of the time. Last summer on a 96 degree day I got stuck in traffic and barely moved in an hour, it crept up to 210 then.