Interesting thread.
The printer's block below was used--probably in a Wheaties' newspaper ad in 1935--to promote the Wheaties brand and the baseball cards found on the backs of their cereal boxes at the time. That was their first year to print athletes on their cereal boxes.
The example card used on the block is that of Jack Armstrong. As we know, Armstrong was a fictitious all-American athlete used in a number of the company's promotions during the period.
The three images are a) The printer's block when viewed directly, b) the block mirrored (to match the imprint that it makes, and c) a scan of the Jack Armstrong card from the back of a 1935 Wheaties box.
Lyman