2D vs 3D
I'm getting way ahead of myself with this head assembly so I put the brakes on to pitch an update. After scraping my initial idea of how the head assembly can tip forward on the neck I came up with this solution which will give me a lot more cockpit room for the crew. There also is a poetic license taken by the artist who drew the front and side reliefs of the Command Bridge. The huge ear discs that contain the head tilting mechanism cannot function as drawn and are of different sizes in the drawing. Never mind though, I have a solution.
I'll start with cutting the forward neck ring to allow the discs to mount flat to the sides of the neck.
http://i.imgur.com/mvwGHMu.jpg
Carving out an outer race for the gimbal head mount pad and gluing on the gimbal bases is what is shown here. The two 0.040th inch discs are 71 MM apart and 56 MM in diameter.
http://i.imgur.com/gkvcxbH.jpg
The bridge truss maintains the distance and keeps the gimbals square to each other and stabilizes the bases
http://i.imgur.com/uFbVKve.jpg
Bottom view showing the forward ring carved out to accommodate the gimbal bases.
http://i.imgur.com/ZpFupBN.jpg
Next, the manufacture of the gimbals mounts. (The area left black in the 2D drawing.)