On a normal Vespa, the tap is closed (C) when it points towards the left (seen from above). Open is vertical upwards and reserve is to the right (R).

However, the VN2 models used a tap made by Dell'Orto that did not use a lever.
It was sitting lower down from the tank so that the disc valve could be turned by hand to the C, open or R positions.

Does anyone know of a similar tap that I can use?

(I have modified a normal tap, but even I get sometimes confused Facepalm emoticon because Closed is now towards the right, Open faces down and Reserve now points to the left .)