I spent about 20 minutes with Eileen Trestain's "Dating Fabric A Color Guide 1800-1960" looking at the samples in the book and at your quilt's fabrics.
Though I couldn't identify specific fabrics, your quilt has the feel of the 1840-1880 period with its stripes, plaids, and umbre' prints. Is it possible, or even apparent that the browns may have been purples at one time? Because the dye was fugitive it may have turned brown and not seem purple at all. A chemical purple didn't appear until 1862.
I also have Trestain's book "Dating Fabrics A Color Guide 1950-2000" and in looking through her examples of the 1950-1960 period, they just don't "feel" like yours look, even though some plaids are evident in both eras.
Hope you have it evaluated by an appraiser who can see it up close; and that you tell us about it! I'm curious!
Jan in VA