How exactly do I fit a bigger screen?

[Trecoolius]

I've been trying to use a different, bigger screen:

But I can't for the life of me figure out the exact parameters I need to edit. I might be biting more than I can chew and the screen might be too big for the case, but asking anyway.

Also, a few related questions:

• Is there a way I can make this wall thicker or increase its distance from the screen?
  
• Is there a way I can increase the distance between the outermost switches and the wall? I am planning to use per-switch PCB's with screws so I need the space to reach in with a screwdriver:
  

Thanks for this awesome project!