I had a conservative class through EGA sometime ago and they say never put textiles behind glass, it speeds deteriation. Also, I would not recommend quilting it at all. Do not use spray glue. You could gently wash it and get acid free board and batting and stretch it in frame. Definitely use color catcher if you wash and use a gentle quilt wash instead of detergent. Older fabrics will suffer if you use modern thread and machine sew on them. The lady that taught the class came from England and keeps things for museums and the Queen.