In my opinion, in the old house it is necessary to leave only the walls and change everything else. If you're thinking about replacing windows in your basement, you might be interested in learning more about egress window basement https://windowtechcanada.ca/requirements-for-size-of-egress-windows-in-basement-for-canadian-homeowners/ because that your safety depends on it in the event of an emergency. Personally, I have already changed the windows in the basement and now I don’t worry at all.