The shift linkage in your photo probably won't work, but it's fairly simple to fabricate something that will from flat stock. You will probably need to extend the length of the shift rods because the side plate of the Saginaw is longer, and shaped differently than the original 3 speed. I have converted a few later-model trucks (55-61) to use the Saginaw, but not one of the early ones like yours.
Jerry
