Here is a auction -not sure how many of these were built ?
No Reserve: 427-Powered 1963 Chevrolet Impala Race Car
Bid for the chance to own a No Reserve: 427-Powered 1963 Chevrolet Impala Race Car at auction with Bring a Trailer, the home of the best vintage and classic cars online. Lot #116,392.
bringatrailer.com