Hi John,
Jim Musick is in the 1933 Diamond Matchbook set but no other "cards" that I'm aware of. For many of the early NFL stars the best you're probably going to do is either a matchbook, a type 1 photo, or the cover of a game program.
Some of these players, like Tuffy Leemans, have newer cards (1977 Touchdown, Fleer Immortal Roll, Swell, etc) that aren't period as well.
Here's the only thing I have of Leemans that's period.
jeff