Having 4 quilts from my great-grandmother, grandmother, mother, I can understand perfectly what you are doing. I love that they are hand pieced - both great-grandmother and grandmother worked in the cotton fields in North Carolina and made quilts using material just like this. I think the sashing around the blocks is the way to go. I would trim as little as possible to make them squares. It appears that you will have puckers but they were made with love. And....by the time you get them quilted, they will smooth out some. Now, my suggestion for batting would be the Warm and Natural cotton batting that you can quilt up to 10" with the batting not falling apart and that would give you a many ways to quilt them a little a part and not need to worry about quilting very closely. Just some thoughts. Hope this helps.