My old Colt had a dimple in the door jamb and until I was enlighted on what it was for I always thought somebody had dropped something heavy on the jamb. I think the trim screw directly above it is where you hang your plumb bob, its a small pk type screw.
thanks, I looked for the dimple. Years and many interiors later the dimple is nowhere to be found. The measurements you gave should work though.
I am about to put the old girl out for the rest of winter, trying to get it flying as well as can be.