What was the standard size of drywall panels made around 1960?
Drywall has always been 4x 8 or 12 as long far back as I know it was first used in the 20’s . By the late 40 and 50’s it was the preferred method it las less expensive and easier to install but the size has been similar to plywood 4x8 sheets has been the standard.
Demo of old sheetrock is much easier than today’s screws, knock a hole stick the framing hammer in the hole turn 90 and pull down the sheetrock will break on the nail lines sometimes sections of the nails come out some not but they come out easily except on oak 2x4. In my youth I could strip an entire bedroom in a little over an hour and a half including pulling nails with a framing hammer and wonderbar . It was more work to pick up the peace’s and toss them in the dumpster or if close to the dump in a truck. But you do not cut the nails.