Have you contacted the Italian Distributor, or one of their dealers?
You most likely need the modified Mistral pin that comes in the Cobra manufactured boards with sliding mast tracks.
Check with the dealers at the link I've supplied, then the distributor, then if all else fails check with Starboard for sources for the pin and uni assembly.
In the meantime, check with any local Exocet dealers.
The pin is usually the same, and Exocet supplies the correct pin and universal assembly with their boards.
Hope this helps,