I got the information from Alfredo Zanalletto Vignale's book "Vignale".
The page is pictured below; the text is not very clear but it says "Another example of the evolution idea to the execution of the bodywork can be seen in the "Antibes", 1953 sports car based on the Fiat 1100/103 chassis; born as a spider with boat style sides in mahogany planking in the sketch, it became a coupé in the technical drawing then only kept some wood trim below the belt-line in the actual execution."
I assumed the mechanials were also Fiat 1100/103.
The other picture is from another chapter in the same book, about VIP customers, and shows "Clare Boothe Luce, United States Ambassador to Italy and wife of the famous publisher, visiting the Vignale stand at the 1954 Turin Motor Show" (note the later date than it says accompanying the other picture).