Old houses can be a major challenge to work on. My last hour turned 115 this year.
The house I have now turned 90 this year. My Dads just turned 100 this year.
I have found old houses are built much more stoutly. My aunt has a newer home, so does my mother-in-law. Both built in the same development. 10 year old houses, cracked drywall, sagging, squeaky floors, and all kinds of problems. They are both in sad shape.
Good luck with your project. Keep us posted. I enjoy watching other people work on their homes. Gives me ideas for mine!