Sorry, I see you were referring to post 300 and not post 306.
In any event, even post 300 is well supported by our history and legal precedents.
This is true today as it was at the adoption.
8 U.S.C. § 1401(G) The following shall be nationals and citizens of the United States at birth:
It is indisputable that a naturalization statute can produce a citizen at birth
Art. II in relevant part: "No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution"
In your construction, a "citizen at birth" by naturalization statute is a "natural born citizen"
In your construction: "No Person except a natural born citizen citizen at birth by naturalization statute, or a Citizen of the United States, at the time of the Adoption of this Constitution"
Since Citizen necessarily encompasses naturalized citizen as well as natural born citizen citizen at birth by naturalization statute there is no difference between the two clauses of Article II. Such a construction is impermissible.