Did a chess grandmaster solve the 340?

The World Chess Federation in Las Vegas, NV is involved in a dispute over trademark infringement. The web site for the World Chess Federation has a profile of its founder Stan Vaughan which includes this claim:

Grand Master Stan’s expertise as a cryptanalyst led him being noted for having solved two of the most important previously unsolved ciphers in the world: The Shugborough Hall Monument cipher for which he had received an award from the Reform Club, and the Zodiac Serial Killer 340 character cipher. Stan was also a National Trivial Pursuit Champion of 1986.

I cannot find any references that mention his solution. Does anyone know anything about it? I am attempting to contact Mr. Vaughan to see if he will give more information about his solution.