Plaster over drywall

[BobB]

I too have a house with this style wall construction. I have come to value the dense, hard, wall surface it provides. Where I have been forced to patch to that thickness, during remodelings, etc..I would do something like rip shims to 1.5 inches out of 3/8 inch plywood, and apply them over the studs, then use 1/2 in. drywall over the shims. But I would suggest not removing any more than you have to, because in my opinion a 7/8 in thick wall surface with a hard plaster finish is far superior to 1/2 in drywall

BobB