Nice Ball. I would imagine the Ball signed by these famous players,would have a value in the region of £100.00 Possibly more to the right person.
I have seen some Perspex Cases especially made to display Footballs and your ball would certainly look better displayed rather than in a Bag in the loft.
If you want to sell it you can place it in Auction on this site. Put a reserve you are happy with. It would cost you nothing to list and you only pay 3% on the end sale price.
Hope this has been of some help.