Even if the jigs etc are all available, there will be a lot of work involved in redesigning the IT systems on the F22 as the original processors etc are no longer available, yes the USAF has a stock of them for repairs etc to the present fleet.
An F22 with updated systems, borrowing some of the tech from the F35, particularly if it had a larger internal weapons bay, would I would have thought be just what the USAF, Canada, Australia and other countries would want, it does create a problem from the UK, USMC and USN though.