At the 1963 Turin Motor Show, the ISO Rivolta company of Milanese industrialist Renzo Rivolta debuted two variants of their new Grifo sportscar.

The Grifo A3/L was on the Bertone stand, while the A3/C debuted on Iso’s stand; only the latter was built by Giotto Bizzarrini’s consultancy in Livorno.

Despite significant differences, both variants sported Giugiaro-designed coachwork, and they synergistically presented a stunning combination of Italian styling, race-developed underpinnings, and reliable, American V-8 power.

Convinced that the A3/C’s incredibly low, slippery profile and front-mid-mounted 5.3-liter V-8 engine configuration could translate into motorsports success, for the next 18 months Bizzarrini made the A3/C under agreement with Iso.

The car neared 190 mph on the Mulsanne Straight in 1965, and the Bizzarrini-built Grifos won the GT class at Le Mans in 1964 and, again, in 1965.

Following the latter victory, Bizzarrini and Iso struck a compromise wherein Bizzarrini would...