Got the Magpul furniture installed. That went well.
As a bonus, my roommate has her dad's old 870. She's already put an 18" tube on the thing and set the 28" barrel aside, and so I gave her the OEM plywood from my gun so she can put her dad's old bird-hunting furniture safely away with the barrel.
Hopefully I can get her to come to a shotgun class and scuff that plywood up now.