Has Shimano produced Ultegra 600 Hub Set, 32 hole?
I'm no expert on Shimano components, but according to Sheldon Brown and Velobase, there were many 32H hubs from the Shimano 600 series: "Shimano added the word 'Ultegra' to their 600 group set in 1988 with the introduction of the 6400 series groupset. Also often recognized by the tri-color stripe on many of the parts."

According to Velobase, this is a 32H Shimano 600 Ultegra hub. I'm not sure if that is what you are looking for. Here is another.