I'd say that unless the pieces are straight geometric lines, your best bet is to use FMQ. Using the walking foot will take much, much longer. Have you done any FMQ before? If not, do up a 12-inch mock up of a block, complete with batting, backing, and top. Draw a picture on the top and then practice doing some echo quilting before you try it on the real quilt top. This will get the kinks worked out and will allow your FMQ to flow smoothly. I always do this before quilting any quilt as a warm-up exercise and it has really made a difference!
Good luck! You'll have to post a picture when you are done. :-D