To save the label I suggest that you contact a local paper conservator in you area, they deal with these issues all the time and can lead you to a proven way to remove the label. You usually only get one good shot and preserving something like this, old paper is more fragile than new but it is the binder that you need to navigate around, it can be as simple as the temperture of the solvent. Also once you get the label off you need to conserve it or lay it down on a new carrier, this is an important decision because you don't want to tear it while it is in it's most fragile state, which is just the moment when it is removed from the stone and hanging by your fingers or tweezers. You need to have your new carrier right at hand. The old "leave it in a book to dry" can lead to other issues.

good luck
Alex