I love the Spalding set because it has a few players you just can't find in any other set - most notably for me, Ed Weir, a great All American from Nebraska who was on the NFL Champions Frankford Yellow Jackets in 1926 with my father. I once owned the Grange from the set but sold it to a devoted collector - in part to buy a guitar and in part because I gave up getting the Friedman which would have completed the football set for me. I think it would be easy to spot counterfeits if you used a loupe and examined the half-tone pattern in the photo reproduction - it's an old style that would be hard to duplicate without a period printing press, in my opinion.
I have to content myself with just a scan of Friedman - another teammate of my dad on the Giants.
I would love to see this collection at the Hall of Fame, but if not I hope to catch it in its travels. It would be nice if in the upcoming 100th Anniversary of the NFL the cards could spark some additional interest in the history of the pro game - especially the teams before WW II.