I have a 57 210 sedan that had the original V8. I had to bore it 60 over to clean up the cylinders and have always had a heating problem that I attributed to thin cylinder walls. I have replaced it with a 383 stroker and a high volume water pump and it is still overheating. The radiator was rebuilt using the copper high efficiency cooling core whhich I was told shhould cool like a 4 core. I have a fan shroud I have added an electric cooling fan and nothing seems to work. It runs cool when your at crusing speed and overheats when driving around in the city. Any suggestions?