Tearing out the plaster/stucco is a dusty mess as you've obviously found out. If you're SURE you don't want to add any other mechanicals in the rest of the walls, you can certainly drywall over them. Hate to disagree, Bob, but if you add the cost of removing and disposing of the plaster I don't see how it's cheaper to tear it out. The additional cost to drywall over plaster is negligible as it just involves a bit of time to find nailers and chalk lines on them, perhaps shim a low spot or two, and flat tape around the trim. Way less mess. I cover plaster all the time, usually with 1/4" drywall. Most older houses have 1"x trim and we hang right to it and flat tape. At the base, just pull the base cap and replace with something thinner after it's hung. No need for removing/ replacing trim or jamb extensions. That would be another cost with 1/2" drywall. at least on the walls. Using 1/2" on the ceiling is often a good idea if the ceiling is wavy. It spans low spots better.