Pretty much any low shank hopping or darning foot will fit, some work better than others, it's a matter of personal preference really. I have one 15 class clone that doesn't like any foot but her own, so I actually do free motion quilting on her with her straight stitch foot. She doesn't even care whether I drop her feed dogs or not. I loosen the presser foot pressure, set her stitch length to zero and away she goes.
For the walking foot you want a low shank one made for straight stitch machines so it's dogs line up with the machines dogs.
http://shop.sew-classic.com/Low-Shan...tch-P60400.htm
Cari