Here is a bit of information for you, all your new engines with high emissions level components are running some kind of extended life coolant, mainly either gold, red, yellow etc. Starting in 2010 and later a newer coolant has been released that is nitrate free which is suppose to be good for 500,000 miles. My opinion is get some VC9 from Ford and get the engine hot or drive it for a few days, then drain the radiator and flush with a garden hose while running at high rpm's or remove the thermostat, then after 20 minutes or so drain again but this time drain the block as well to remove the iron system cleaner or (VC9) which can be corrosive!!. Grab some fleetrite extended life coolant from a local heavy truck shop and fill with that. My oil temp alone has dropped 20 degrees on my 2001 7.3. Hope this helps your 1972 Nova!! LOL