Hi Daniele,
Your carburettor is one that would puzzle a lot of people! You are correct in what you say about the formation of AMAL, but after 1928 AMAC and Binks carburettors were still made and sold. For example, Norton used Binks-branded carburettors (which looked very much like AMAL) on some models in 1930.
AMAC carburettors were used on some British bikes in 1929 and 1930 - almost always on the sporty models. The MD series were not uncommon (the 10MDY might be seen on an early 1930 Model 90 Sunbeam, for example), and the TT series was still around (on top of the line sports bikes) mostly as the 10TT25.
You carburettor is neither of these. The number 6/001 stamped on the body is an AMAL designator, and a near-identical AMAL 6/001 carby (fitted with an AMAL fuel bowl, with AMAL stamped on the top) was used on a number of 350cc overhead valve British bikes for 1930, for example Raleigh and Sunbeam.
AMAC carburettors disappeared from British bikes around 1930, but they were used on the continent well into the 1930s. I'm not sure where they were made.
Anyway, I think your 6/001 AMAC (with French writing on the fuel bowl lid) is just the thing for a 1930 model 350 OHV Moto Guzzi. The bore is only 15/16" (23.8mm), so it might be a bit small if your bike is a 500.
How about a photo of the bike?
Cheers
Leon