cast iron water pump vs aluminum pump

I,m running a 408 in my 66 Dart,stock 2 core rad(recored)7 blade fan,no shround,no thermostat.I have M1 intake,Eddy heads,Eddy aluminum water pump.I alos added 1 liter of BeCool additive to water(racing)My car runs very cool and have never seen it past 180 on a 90 degree day.Your either too lean or timing is off?With the new 3 core alumi rad you should be running cool.Maybe try some of the additive?