Most frame shops offer UV Museum Glass which blocks around 99% of UV radiation and is virtually invisible. It can be several times more expensive than regular glass, but for high value pieces, its worth it. An option for card display is a hinged shadow box with card ledges. Places like Hobby Lobby can make these for less than you think, particularly if you use a standard frame. If you already have a display, they can replace the glass for better UV protection.
Chris
www.antiquefootball.com