Radiator tips for 67 Dart with 440

I've got a 67 Dart with a mildly built 440, aluminum heads. Constantly have had cooling problems ever since I bought it. Main issue is the clearance I have which is a snug 5".
Proform has been mentioned to me since they have the slim fit radiator assembly at only 4" including the fan and shroud, but don't want to drop that amount of money if it's not for sure gonna fix it. Thanks!20220419_210122.jpg