Since the rest of the black is thick and rich, I think the 'Skowron Blip' on the McFarlane card is just an unrelated gray area, or toning or something, so I don't believe it to be a match...
1966SKOWRON590comp02.jpg
How funny is it that on the back of Moose's card, although he won multiple championships during more than a decade in the majors, the highlight they chose to include harkened all the way back to his minor league days??