@Bud - Care to share a good method? I need to stay close to the wall because that wall is continuous with a staircase and I want the wall/staircase to be on the same plane.
I built 2X walls in some other areas of the house (which was great for running my network and electric) but I can't on this wall because it is continuous with the stairs. I would end up with a 2.5" vertical lip where the stairs enter the room. I guess I could move the stringer over a couple inches and have 33" wide stairs. The stringers are hung but I haven't completed the stairs yet. That would also add some depth to the windows, though...Can't see it, can't imagine what you are up against.
If you say you can't attach firring strips because of loose material and irregularities in the existing wall then you can basically build in front of the existing wall.
If you say you can't attach firring strips because you don't have the necessary room then that's a different issue.
I've never seen a wall that couldn't be cosmetically improved. Even 2"X2"'s can be used in most cases. Basic 2" X 2" [bottom plate] and [top plate], then 2"X2" 's for studs. Shim the studs to the old face for additional support.
Maybe I'm missing something here.
Maybe a picture or two would be beneficial.