Taking this direction, use a spell to create a statue mimicking your disintegrated party member, stone to flesh, raise dead, and enjoy your party member with a new body.
Or, you can craft yourself a younger body using the method above, cast magic jar and transfer to the new body, have raise dead cast, cast magic Jar again and transfer to the old body. The first cast ended when you returned to your body and when the second cast ends you return to the new raised body as your brand spanking new young primary body. The best part is that you don't fight over the body with someone else, so no will save.
Magic jar only requires a body, it never says it has to be inhabited or living.