I just received my new Pan 312 and love it!. However, my wrist is too large for the regular straps and Tourneau tells me they can't swap em out. The Panerai Boutique said the same thing (which kinda sucks IMO).
Anyway, I have the OEM black crocodile with white stitching, the OEM rubber strap and the OEM Carbon Fiber strap all in regular versions (24mm width) available if anyone has the equivalents in the longer version.