The PW1 is in a bit of a weird place if it's already running 5.6.1.1, but the gist of it is: you can downgrade it (possibly only via the dirty unplug method). Looking into old posts dating back to those days might help. (EDIT: Re-reading your first post, I assume you've got this covered, though

).
Depending on how far you downgrade it, you then get to choose between either the applicable legacy JB, or a Factory JB as explained in the Open Sesame thread.