I have a reproduction of a Sipp catalog, what year it represents I know not, but it looks to be early century in style and tone. In it, they do list blueprints as included with the casting kits.
That being said, I have never seen such a set offered anywhere, but if anyone on the Forum has a set, I'd bet on it being Gil.
You may be right, Daniel. I don't know quite where they are after our move but I do believe I have a set. When I find them I will let you all know.