I think if I was going to go to the effort, I would do this slightly differently...
I would have extended the stick from the gimbal, mounting the gimbal and box on the floor the use about a 24 inch piece of wood or something to extend up from the floor and then re-attach the original stick handle to the top..
In this way you would get the longer throw of a WWII fighter's actual stick and would gain a lot of precision movement in the stick...
Of course, I don't know if a Saito stick is analog internals... If its digital that wouldn't go very well... I know with my CH analog guts it would work great.
Anyhow, great work on that chair, I wish I had one! (except with the stick mod I described

)
I think if I was going to use an unmodified stick as you did here, I would have set it up 'side-stick' like a modern fighter so the throw would feel more natural.