In a 60-year-old house, nothing is straight, square, plumb, level, or parallel.
Corollary – Putty is your friend.
Because nothing in a 60-year-old house is straight, square, plumb, or level YOUR work should focus on being parallel, rather than straight, square, plumb, or level . Because if you MAKE it straight, square, plumb, or level, the existing “quaintness” will make your work look cockeyed.
Framing carpenters build to the nearest eight (of an inch). Finishing carpenters build to the nearest sixteenth. Luthiers build to the nearest 100th. And boat builders build to the nearest boat.