If you were sitting in the cockpit and placed your left hand on the center of the panel shade next to the gunsight, and then placed your right hand to where it's back was touching the glass at the top - it would be around 175mm, or aprox. 6.8 inches. a compact disc is approx 4.75 inches as comparison.
Anyway, after comparing some recently found engineering diagrams to the 3d model, I did find an error, which is that the cross bar above the armored glass - It should actually be an inch lower than it currently is. Which would give the following rough results: 109A.jpg is the current layout, and 109b.jpg is a rough photoshop of lowering an inch.