On a 600HP street BBB, I use a cheapo AL/Plastic radiator from a 90’s GM vehicle, 160 stat, cheapo parts store water pump, locked timing @ 34, 250 cam, LT1 starter, no start retard, 11:1 cr, stock fan, clutch and shroud and drive the car on the street with no overheating or even “temp creep” in traffic. If you are heating up in traffic, the most likely culprit is not enough airflow through the radiator. Is the fan clutch working properly? Does the temp drop back down when you get on the highway? You may want to double check your fan clutch, drop your stat temp to 160, and lock your timing.