Nothing new to report, having checked my books.
I seemed pretty sure at the time I posted this that it wasn't a re-post (which it would have been if it had been that original 6C 3000 Fangio) but I can no longer find any proof of that. But I accepted the ID as the 3000 without arguing the case for it being a 1900SS so maybe I was getting confused with something else. Frankly, I don't know. Sorry.
Perhaps an Alfa expert can throw some light on this.