Wow, it's been around that long and I've never seen it. Much cuter than Sunbonnet Sue! I agree I would add some black embroidery to outline a sleeve.... You can buy authentic 30's fabrics, you don't have to use reproductions unless you just want to. Ebay and Etsy are good places to look. Search for "vintage feedsack fabric".
You have a real treasure there. The embroidery work is awesome on it. Can't wait to see how you make it up.