Alfa Romeo 1900 SS Boano
That is indeed what it's labelled as in most of the very few places you can find anything about this car.
There is some discussion that it was actually called a 2000 SS, but it was made before Alfa officially called their engine a 2000, although it had been bored out to 1975 cc - it was nevertheless still called a 1900!
i did also ask in my question for its date, but since I cannot actually find that out for definite myself I can't hold out for that! I believe it must be about 1956.
Good find.