A word to the wise -- from the sad -- I'd advise having the ball coated somehow (laminated?).
In the 1977 season, I won a raffle and got a ball signed by the whole team. It was the year before Banks and Dennard, but it DID have signatures from Gminski and (most importantly to me) Spanarkel. I stored that thing on the top shelf of my spare bedroom closet and never touched it. When I moved several years later and I looked at it again, all the signatures were gone. Evidently, the liquid in the ink/marker had evaporated and the signatures had simply turned to dust.
Don't let this happen to you . . .