I used my Bb clarinet reeds on my recently purchased sop sax until my sop reeds showed up. Clarinet reeds do have a longer vamp and are a tiny bit narrower (.53" vs. .55"). If the tip of the clarinet reed is trimmed to make it the right length, it shortens the vamp too much and would still be too narrow. So, you could make a clarinet reed out of a sop sax reed (although it would be .35" too short), you can't really make a sop sax reed from a sop clarinet reed even if you spent the time to rework the vamp.
Mark
Mark