I have a bunch of 5/8" flat reamers. I was able to run them through by hand without a handle.
I could not get the other part of the stick through. I did have another 5/8" steel tube that was a little smaller. Another argument for polish over paint- I put some F9 on the bushing and tube and polished it up to a larger hole size.
After polishing with the tube, I repeated the process with the control stick part. Then I cleaned out the F9 and made this jig to align my stick halves.
The plans specify some small clearance to limit fore-aft movement. I am going to make it tight and sand as required.
Adam has been busy so I am doing other things besides rigging the wings.