I liked the appearance of the aged plaster wallpaper design joining directly with the flooring in the mockup photos I've been using, so that's what I tried to accomplish in the finished room. I had previously stained the red oak flooring with Minwax Dark Walnut. I burnished the surface with a scrap of paper bag and then sealed with two coats of Delta Ceramcoat Matte Varnish.
I painted the board, finishing the ceiling for the first floor in crisp white to reflect light. I stippled the paint to create a delicate texture I thought would go better with the aged appearance of the wallpaper. The texture also hides the wood grain. Since there's still work to be done on the main floor, I will leave the ceiling board loose for now.
Exactly the look I wanted.