i dont even know why they make 26 to 31.8 shims. waaaaaay too big. do yourself a favor and get parts that fit. isnt 25.4 = 1"?
check out your LBS and ask for a spare parts bin or something. since you're in so-cal, try checking out open road bicycles in pasadena, ca. awesome place. bought an RC 1" threadless 120 mm 26mm stem and nitto 25.4 to 26 shim for $ 25. they have A LOT of used parts