The first thing to realize and accept is that under your circumstances, switching to a Gray surface would be very advantageous. Do not doubt the validity or necessity for such a change.
The second thing to get down with is that using Drywall is not just an accepted practice, it can be at times the very best route to take.
Less cost - extremely easy screen placement - screen is almost as indestructible as the wall....and certainly just as repairable. All you have to do is make sure it's as smooth as possible.
Oooo...that 'ol 90"er is a wrinkly mess.
It would seem that 90" will be your new screen size also...or very close to that.
would be the brightest mix to suggest. However Silver Fire
would work best to mitigate the reflections those White surfaces bring to bear.
The Ceiling is not nearly as troublesome as is the Soffit / Fur Down. But both need addressing.
Although tastes can and do differ, I have not found many who remain adverse to creating a darkened "Shadow Box" affair at one end of the room after having done so, and none ever fail to see / realize the advantage such an action affords the performance of the PJ / Screen combo.
You don't need to "Blacken" those surfaces. Simply Spray the first row of ceiling Tiles directly over the Screen, and a like depth of the Soffit the same color of the walls (in "Flat"). Or perhaps the same color only 2-3 shades darker. That will do wonders for abating...if not actually eliminating your reflection based issues. And...if you produce a new Silver Fire v2.5 3.0
Screen and also address the ceiling / Soffit, you'll make that 8350 perform like a 5020