My wife, who makes a tidy sum on the side by designing and making scrapbooks for people, suggets that you use a product from the Provenance Company called "Paper Saver". It will deacidify any paper and preserve it for centuries. It isn't cheap but it works wonderfully. You can get it at any Arts and Crafts or Scrapbooking Store. If not, their number is 877-829-7392.
Have you considered scanning the music for yourself and donating the hardcopy to an organization with professional archivists and suitable storage facilities? It's probably even worth a tax writeoff.
