I was in Graves Hobbies in Orlando on Sat. and they had rudder horns that were made for pull pull. It had a piece that wraps around the leading edge to put both exactly equal. As you know, equal distances and holes lined up exactly with the hinge line means perfect pull pull (both stay tight thru full movement without needing stretching.) Seems like these on the rudder and elevator would be dead easy to make the perfect pull pull. Unfortunately, I do not know who makes them, I'll have to look next time I get up there.
Tom onrecess PB#143