I am remodeling my bathroom , trying to add space by moving my toilet about 5" over bringing it closer to the exterior wall. Problem, old house, cast iron pipe and lead pipe. the exist iron pipe coming from the wall is facing diagonally with, what I think is brass connecting to the lead pipe, the lead pipe is extended about 19" out. I am trying to move the toilet closer to the exterior wall, to add space in the bathroom. The distance from the existing opening to the back wall remains the same, I want to move it 5" over, keeping the same distance from the back wall. I already started to cut the lead pipe. I would like to remove the lead pipe and add pvc. How far back should I cut the lead pipe, and what about the brass connecting the lead pipe and the cast iron pipe, should I cut that off as well, if so how would I connect the pvc to the cast iron pipe?

You will remove everything back to the cast iron leaving a bald end that you will attach a Fernco Shielded Coupling ,(see image) to convert to PVC.
You may then use PVC fittings to complete your move. Good luck, Tom