Cutting into footing for plumbing?
After consulting with a plumber, he advised to leave the footing alone. The first reason was it could potentially lead to foundation cracks in the future, or compromise the wall itself. The second reason is the concrete is so old, it would be a huge undertaking to try and remove any of it.

I opted to move my wall towards the center of the house by 6", which makes the bathroom smaller but negates the need to mess with the footing.