You should also remember that in 70the lower outlet changed. If you are running an aluminum water pump then it's the later style, if you are running an iron water pump it's the early style,

If you are indeed running the later A body radiator like you think then

https://www.classicindustries.com/product/1972/dodge/dart/parts/ma2228.html

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.