The size of the blocks is one determining factor. SID will work, provided the blocks are not large. One other option would be to place an oval, circle, square or some other geometric shape closely around the redwork, then a 45 or 60 degree cross-hatch from the geometric shape out to the SID in the sashing. Some of the blocks would look best with a square or rectangle. Others would look better with an oval or circle. I would probably use the 60 degree cross-hatching myself. You could use a thread color matched to the background for this.