TY,
This is a major problem with many of the Classics. While I have used a Ultra Hobby clevis in my "Top Hat" that's is a modern airplane with lots of room built in to the design''
The "Carousel" that I build had about 1/4" clearance for controls inside the rudders. With the high tail, it made adjustable items next to impossible. For clearance I cut a curved slot in the rudder sides tha follows the horn travel, to clear the horn and Hayes clevis, and then covered the slot with silkspan. That gave just enough clearance, and after it was painted you couldn't see it.
The "Sea Vixen" also has horrible clearance problems in the aft area of the rudders, where the horn has to travel. I have the controls closed up now, but I will be opening the tops of the booms again to try to get smoother operation, since I am not happy with it. This has been the most challening project I have ever done. but for that reason it is also the most interesting project, because it is such a big challenge.
I am assuming that your "Knight" will also have to have a large braced "Z" in the pushrod to get up to the high "T" tail.