Sucks that the Nitto M106 did not fit the 7400 quil stem, but the classic bars might actually fit the frame better.
This is beautiful! You might have thought of this already, but did you consider matching the M106 bars with the Nitto Dynamic stem? I used this to replace my old Cinelli set-up and much prefer the bar shape. (I also still have the Dura Ace AX aero seat post on this, lovely except the graphics started wearing off about 20 years ago!)
Didn't Nitto make the Dura Ace stem on behalf of Shimano? So it's a sort of match anyway and has the same finish. No idea about out front mounts, I've now got a standard Garmin mount attached the right handlebar collar.
This is beautiful! You might have thought of this already, but did you consider matching the M106 bars with the Nitto Dynamic stem? I used this to replace my old Cinelli set-up and much prefer the bar shape. (I also still have the Dura Ace AX aero seat post on this, lovely except the graphics started wearing off about 20 years ago!)