how much electric fan cfm??

My 69 Dart is a 360c.i./approx 370hp with a heavy cam and in traffic it wants to go up to 200-210. As soon as I get going 20 mph + it cool back down to 180. The cam is killing me in town, not enough rpm. my choice is either a 3 core or a electric fan? The radiator in the car is a almost new 2 core bought by the prior owner and I put in a new fan clutch and it still is hot in town. This seems to be a common problem. Young Mr. Goodysgotacuda has a nice setup. Where did you get it. My radiator is a 22".