This is the 12mm Pin version of the Polini kit. If you are running a 75cc kit on your Vespa, it is a good idea to have a beefier piston pin anyway. So, during the rebuild, pick up a new 12mm crank to go with it. Amazing power for your lil Vespa.
12mm Piston Pin Version
Polini power on a little Ciao. 46mm
This is a big ol kit. You will need to bore out your case to make it fit.