Welcome Nasos... You definitely should join the GB club.
They've been a fantastic source of assistance to me with my '55 Turismo Rapido
There's a coupla Frenchies here with 60s gtls who I'm sure will chip in with their two centimes worth!
Great people here one and all.
MVista's tips are excellent as the guys at Dellorto are very helpful but you'll not find a carb body that way.
eBay is going to be your best bet.
What size carb is that? Maybe I can keep my eyes out for one....
For the speedo you might try http://guzzino.com