Best coolant for our 60-70's Mopars?

I don't believe brand makes much difference. Prestone and Zerex are 2 famous brands. But I have used manufacturers brands and Farm Fleet brand too. For general purpose antifreeze and coolant use mix 50/50 with water. Some use distilled water because it doesn't have minerals in it. You can also but premixed which is 50/50. Get a antifreeze tester and check it after you run the engine to circulate it. Because you live in a warmer southern state the anti freeze protection isn't as important as us Northerners. tmm