I will contact Rizzini USA.
From looking into the action, it would appear that "fewer" parts would be needed to go to a double trigger mechanism. The barrel selector will need to be locked, the inertial block removed, a new trigger axle installed, but the hole for the axle exists, new triggers located, etc. I already have a set of unfitted triggers as I mentioned above.
Let me see if I can find the parts.

The only constant in life is change.