Excellent work ! Replacing the lower back panel is tedious, but needs to be done. Takes a lot of time, but worth it in the end. Like with all restores - take your time.
A tip with Fathom and Centaur - Be CAREFUL once you have painted the cabinet as the top ball gate WILL chip off a small section of the headbox trim. This can happen raising and lowering the cabinet.
Keep up the good work !