The car originally appeared at the Turin Show in November, 1971. It was announced as a series production model, but Coriasco changed his mind and it remained just a one-off.
From Alessandro Sannia's excellent new book Carrozzeria Coriasco, just published:
"The following year, the Fiat 127 Coupé was unexpectedly displayed at the Turin Motor Show again, simply repainted in metallic grey and up-dated with black plastic bumpers. This was its last official appearance before disappearing into oblivion forever."
I think this answers your questions!