It should be noted that while Edmunds heads were popular on various hot rods, the aluminum alloy of the day could be problematic over time because of combustion heat. K-F had this problem with their experimental aluminum V-8 motor. Also, as anti-freeze chemical composition changed over time, you had new corrosives introduced into the mix. It was for that reason that GM finally came up with DEX-COOL and even that has a problem (by around 100,000 miles or so, the stuff starts getting the consistency of cheese and begins to look like same).
We've run DEX-COOL in the Lumina from day one, we have over 216,000 miles on the car, and outside of the head deck problem at 105,000 miles (reflection of that 'cheese' thing) Barbara and I have had no problems with water pump, water lines or other coolant problems.