I have not conserved/repaired any quilts, but I would agree with Judith 1005: I would back the butterfly blocks with a lightweight iron-on fusible. I would also remake the sashing. There are plenty of quality solid fabrics now that you could match the colors fairly closely. Regarding finishing the quilt, I am not sure I would. I think I'd leave it as just a top and enjoy it as a family heirloom. Just my opinion.