Hi Mark,
I don't own any of them personally yet but sometime back I was looking into purchasing some football art for my office. I looked at the Bob Peaks Sports Illustrated signed lithos from the '70's (Grange (I owned once & regrettably sold) & Unitas) and came across a website detailing the Harper's woodcuts done by an artist named Remington. I can't find the article now but did find this website (pretty neat). From what I remember, the Harper's prints were valued anywhere from a couple of hundred to a couple of thousand dollars, depending on the size and subject matter. If I find the article again, I'll post it.
Again, congratulations!
http://www.lostcentury.com/#jp-carousel-1357