It's been a while, but I did manage to pick up two new cards, including one of the keys to the set; #16 Harry Lowrey, and #276 Ken Raffensberger.
Lowrey died in 1986, so he is not easy to come by. Growing up, he worked as a child actor and was one of the original members of Our Gang. This was the first one I'd seen in the almost two years I've spent building the set. From what I've read, Stan Musial had a very tough time with Raffensberger, even calling him the toughest lefty he had ever faced. These two bring me up to 156 / 274 (56.93 %).