Well, unless I want to introduce a generational loss across the entire trilogy by ripping the finished edits themselves, at this point it’d probably be easiest to manually trace and rebuild the entire trilogy by overlaying them by a guideline proxy video track ripped from the existing finished edits.
It’s just not worth it, not without the truckloads of free time I once had. Those FCP7 project files are houses burning down caught in suspended animation.