dragon462, I have watched this thread with great interest. I would suggest that you spend $100.00 and buy a FlowKooler water pump. I have known several people, not all mind you, that have had trouble like you are having with the Edelbrock pump. I am not saying they are bad but there is good and bad in everything. With all of your effort I would spend the $100.00.
The only time I have ever had a heating problem with an FE was when I used a pink or yellow
antifreeze. I now only use green. Yes, I have had some very fast, low 11 second 427 in a 3700 pond car, which was pretty fast in the early 70's.
Good luck and I hope you figure out your problem. I forgot to ask, do you have the by-pass hose installed between the water pump and the intake?
Byron W.