Steve,
You already have springs that look like they will work just fine, so I don't know if you will ever get around to replacing them. However, in my opinion, the Sycamore is so beautiful, it deserves something nicer looking than hack saw blades.
When I made my 8 x 20, I pretty much copied the way that Kodak did it on my 8 x 10 2D - that is to use brass rather than some sort of spring steel. Brass is actually pretty "springy" itself. I used sheet brass from home depot that is used for kick plates for doors. I cut into strips about 1/2" wide and used two layers - one on top of the other just like Kodak did.
The brass is easy to get, easy to cut, and looks good. However, there is one drawback. That is that you need to get a special saw blade for your table saw to cut the brass, one that is used for non-ferrous metals. For a good one, it's going to set you back around $75 or so. For a cheaper solution, you might consider cutting it with a dremmel and filing the cut edge smooth. I also only made one strip per side rather than the two hack saw blade strips you have on yours. Here is a photo of the back. You can also see that the top strip is a little shorter than the bottom strip. These two strips of brass on each side of the camera back seem to apply just about the right amount of pressure to the holder.
Hope this helps.
Dan Dozer