FlowKooler or Milodon water pump

I have used Flowkoolers on my early As for several years and had good experiences with them.
Many years ago I worked at a NAPA store and an older semi-retired gentleman was also working there part time. He had, in the past, worked for Gm, Ford and Chrysler and was sort of a cooling engineer. He moved to town with Detroit Diesel and was their cooling specialist before coming to the NAPA store. One day I asked him a question about water pumps for V8 Mopars and I started receiving a cooling lesson for about an hour after work for several days. One day we went to the water pump section in the NAPA store and took down all of the water pumps for LA mopars. There were six Rayloc rebuilds and two Balkamp new ones. He measured the depth of the impellar on each of them finding quite a range. Even the two new ones were quite different. He explained that LA Mopars use the timing cover as the rear flow control for their impellars. Those pumps with the impellar pressed on further than specified would not provide designed output. He also told me that in the days when he was involved with race cars they would cut a metal disc and braze it to the back of the impellar to ensure proper coolant flow. The next day he brought in a few different impellars that he had used for training over the years. The ones he claimed to be best had a full round disc on the back of each one. Well, years later I saw that Flowkooler was using the type of impellar he suggested so I got one and it worked well. Ive been using them ever since.