You might have some luck with fake books - according to the Seventh String site, there’s a “Peaches en Regalia” in the Old Real Book, Vol. 1.
The big drag is - it’s in the nature of fake books that they’re listed by title, not composer. Going through Zappa’s massive catalogue one title at a time is not going to be quick nor easy.
It might also be worth checking for some of the sheet music of Zappa. The grand-daddy of them all is the Frank Zappa Guitar Book - at that site, Amazon seems to want me to believe that there are books of Overnite Sensation, Apostrophe, Hot Rats, and One Size Fits All available.
When I did a Zappa tribute show with the Montréal based Association pour les Créations et Récherches Electro-acoustique de Québec (ACREQ), Gail Zappa made the charts available to the arrangers, but she and the family were getting their royalties, and the whole show was based on the crème de la crème of the Montréal New Music scene performing. The family went out of their way to assist us. With Dweezil doing ZPZ, those charts might be a lot harder to obtain.
The earlier stuff is easier to lift than the later stuff; that’s still a level of ear-training that’s way beyond what I can do…