My excuse I don't have the Braden book. But I have looked on what Ghia did on Abarth, and found these 2 from 1953. Is it these it about, the one on Fiat 1100 basis the other on Simca Aronde bases.
The Abarth Renault Fregat was produce by Ghia, and Scaglioni was designing for Bertone at this time. Bertone produced Abarth 215A and 216A, a coupe and spider in the same design