Help 360 getting hot

I had the same issue with my 72 Dart its also a 360 built to about 400HP. I replaced the radiator with a new after market Aluminum one (Champion brand I believe). The car would still heat when cruising the town. Then added a 16" electric fan to the front of the radiator (It blows back toward the engine fan) and found a place to mount a toggle switch in the car to turn it on when needed. I don't have to run the fan much but its nice when its needed. I also only run about 20% anti-freeze which helps if you can keep it out of cold weather.