As I read it you said this was locked until Max Pershin's next reply. He has replied now and you haven't re-locked it so it would seem to be unlocked?
This car appears in Alberto Fornai's Carrozzieri Italiani as a Boano.
2 Alfa 750 Competizione models were produced in 1955 (as Max Pershin says). One was the Spider Competizione Tipo 750 Corsa, and I think that is the one Max refers to, with fins.
The other one, the car pictured, is the Spider competizione corsa grezzo (which translates as crude competition racer) which was a much less refined pure race car. The chassis of both cars were constructed by Abarth.
Tomorrow I will post the page which says all this in Italian and (poor!) English, but according to Fornai it is definitely a Boano car, the Tipo 750 spider competizione corsa gresso.