63 Dart overheating issue

I had the same problem with my 63 dart . I tried everything. As a last resort, I pull the water pump and compared it to the one I took off motor during rebuild.
The impeller on the new water pump was smaller than the old water pump. I reinstalled old water pump and problem solved
You didn't happen to snap pics of them did You?? Where did the pump come from, & what branding did it have?