You need the original bill of sale to get an in-transit permit from a registry. Maybe some registries are cool and will take a scanned copy, but the ones I have local to me have insisted on seeing both printer ink and pen ink on the same page. That's not an issue if you don't plan on driving it home. It's a tremendous pain in the dick if you do plan on driving it.
You don't need anything other than a bill of sale. Your insurance will probably take a scan or picture of it, and then you need to get a request for an OOP and then an OOP like you said.
2007 GMC 2500 Duramax
1991 GMC C1500 350
1981 GMC C1500 454