There was a full article on the Hiller UH-12C in Pilot Magazine May 2002 p58. I think that will answer a few of your questions. If you haven't got one I could send you a copy of the relevant six pages.
The provider of the Hiller for the article was a chap called Warren Chmura of Southern Aircraft Consultancy, whose telephone number is 01763 786 032. He looks after Hillers on the US register. He might be the same chap you are referring to on your post.