[HasselhoffsCheeseburger]

I would include any Exhibit that can be pinned down to one particular year for issue release (early stuff). I would not include the latters (47-66).

I would not include the Brown & Bigelow or Detroit Free press as those are supplements/premiums.

For me (and there's obviously no textbook definition), a rookie card should come from a set; meaning there should be multiple fighters/players issued under the same release. Otherwise, why not just include dated photos?

The '71 Barratt Ali shouldn't even be considered. There are dozens of Ali cards prior to that no matter how you define rookie card.

The more important question is what constitutes a "card?" Archie Moore has 1948/49 issues (and early 50s) from outside the US, although they're not rectangular.