Wow! Now that is truly a wonderful heirloom!!!! Wow!!
My suggestion would be to take it to a quilt appraiser. This will cost about $30. The appraiser can date the quilt from the fabrics and other telltale signs and they can put a value on the quilt. The more you know about the background of the quilt, the more it is worth. It's a good idea to do this with any heirloom quilts, in case something terrible happens (fire, flood, dog...). There is no way to replace such a treasure but if something does happen it can really help.
Piece ~ Tiffany