Go to a search engine and look up just who was the last “ grandfathered” President and when he was born. Tell me what his age would have been upon the eve of the Revolution and provide a source, any source, indicating he was naturalized.
You can't because he wasn't. Naturalized individuals have never been eligible. He was an original citizen, therefore he was under the so-called grandfather clause. There is no reference to place of birth. He was the child of a citizen of the State in which he resided, had not taken up arms against the Patriot cause nor aided the enemies of it.
Other than a few Cherokee ancestors, I descend from nothing but original citizens, some of whom were the Gernman-speaking people of whom I spoke. I know what I'm talking about.
“Naturalized individuals have never been eligible.”
Consider this hypothetical:
In 1784, a 35 year old London-born man moves from England to Massachusetts and in 1787 he is naturalized by an act of the state legislature to be a citizen of Massachusetts.
Would he fall under the grandfather clause?
Under English law at the time, he would still be a British subject.
Under the Constitution would this disqualify him?