Probably the only harm you might do with any vinegar wash is expose issues in your radiator at worst. But then the rad needed help. Vinegar is a very lite acid. We drink it everytime we eat anything pickled. Opinions are interesting, usual not based on experience.
Best thing you could do it remove the heads and hog out the water jackets with water and a coathanger.
People said never ever use muriatic acid to clean a hit/miss hopper. It'll eat the motor over time if you don't neutralize it. Diluted with water it worked great for the hit/miss. No issue 10yrs now. That would eat a rad quick though.
https://www.youtube.com/watch?v=YsVnPdRjCU4
Best of luck!
.