So, long story short...
Wife and I were fixing some damaged walls around the fireplace and noticed the brick at the top starting to come loose, we wanted to update the fireplace anyways and decided to take the brick down to about mantle height and have a nice clean flat sheetrocked wall above the brick fireplace/mantle.
The white brick seen in the photo between the studs has some pieces of brick and a lot of mortar that is protruding into the room further than the studs you see on the left and right which would make a flat sheetrock wall nearly impossible.
Is this brick just filler and I can remove some of it to frame out the opening for sheetrock? or is it Firebrick? Our other option is build the upper wall where the brick facade used to be so that we can get a flat wall, the downside is that it will still protrude as the old brick did and wont look as good as we'd like (basically instead of brick to the ceiling it's drywall).