I wanted to pass on to all who have been looking for a hot water shut-off vacuum valve, after much searching I found that Ecklers corvette section makes two versions one for the 64 late-67 years and one for the 63-64 early years. I have not received my order but by the picture it looks like a good match.

http://www.ecklers.com/corvette-hot-...late-1967.html
http://www.ecklers.com/corvette-hot-...1964early.html