Observation

 Drywall finishing work is a lot like modeling. You spend a lot of time waiting for things to dry.

Where the closet wall came out there is a lot of variation at the joints where the old closet wall meets the old room wall. On one side the door frame occupies much of that joint, so the variation is not as pronounced. Just above the door is worse, but not really so bad.

On the other side of the room, however, the surface of the room wall stands about a quarter inch proud of the surface of the closet wall. To make things worse, the drywall on the room side is crumbling along that edge, so it isn't firm against the wall studs in that joint area.

To remedy (but not really correct) it I am sanding the room wall down into the plaster about an eighth of an inch at the edge, feathering out six inches or so. I will then build the closet wall out about an eighth with drywall mud to match the sanded surface, feathering that out six inches or so as well. When I am done I should have a 12 inch surface, six inches on each side of the seam, that gently transitions from one surface to the other. 

The wall will never be straight all the way from corner to corner, so my goal is to simply smooth the transition and then I can disguise it with benchwork and scenery. In order to get it done, however, I am having to drive or pull nails and sand about 2 vertical feet of the wall at a time along the seam and then fill with drywall mud. Because the mud is so thick it takes a long time to dry. I will then have to sand that down, fill in the low spots, let that dry, sand it smooth again, and repeat as necessary to get that smooth transition. 

I expect this will take a few weeks on the days that I am not working. Fortunately there is still much to do while the wall dries, so that time is not lost completely. Perhaps by this fall I will have the room walls finished enough to paint, then I can start building the layout.

If it was easy everyone would do it.