I had always heard they made two. Probably didn't make anymore because it took 3 men (all sitting in the back seat) to shift.
Here's another view of one of the weird flipper-wing prototypes. Hurst was obviously inspired by the innovative Jim Hall 2E Chaparrals from 1966/1967. I doubt a moveable wing would be very practical (or effective) on a street car, but hey, give them an "A" for effort.