Not 1978
One more try!
I was mistaken; it was in 1975 that Godfroy was looking for employment with several large companies. (He was finally hired by Peugeot in February, 1976.) However, he had kept himself busy creating designs throughout 1973-74, so the potential gap ranges from 1973-1975. Hmm...
As this design reflects the influences of Gandini/Bertone's Alfa Romeo Carabo (1968), Lancia Stratos Zero (1970) and Lamborghini LP500 (1971) (and possibly Giugiaro's Maserati Boomerang of 1971), and looks as though it could be contemporary with the Lamborghini Bravo (Gandini/Bertone, 1974), I'm going to go with 1974.