Wow, some really nice items. Adam, that boxing woodblock is fantastic and I hope at some point that you come across the associated publication.
The below woodblock has nothing to do with sports but was very intriguing to me given my interest in woodcuts. It depicts a French statesman by the name of Eugene Rouher. The detail on this piece is truly incredible and it was later used in an 1840's Police Gazette (still searching for the exact publication date).
The second piece is not necessarily 'one of a kind' but I have yet to see another example come up for auction. It's an 1874 Daily Graphic woodcut depicting the Philadelphia Atheltics. The woodcuts of McBride and Battin are referenced in this
REA auction as the basis for the 1874 "Golden Ball' cigar box label.