JC Whitney says they have patterns for just about anything. Also eBay seller "goliners" has em for '63-'73 Rivieras. They may have them for wagons too. Just do a seller search and ask 'em. I hope they do. I have a line on a '63 Invicta wagon and may need one some time. Good luck!
CARS, Inc. in NJ sells headliners for these cars, but there is no specifici mention of wagons. Sorry o No: http://www.oldbuickparts.com/cat610/61014.pdf
Talking to the seller of the car, the headliner is the only thing miss in the whole car. Also an interesting tid bit he claims that the wagons where not build by GM, they were actually farmed out to a company called Voila(sp?) as 4drs and converted. Don't know if its true but a man with 3 Lesabre wagons and 4 other 61 Buicks probably should know. He was saying something about using a fiberboard type headliner not a bow type like most GM products of the era.
I've read about the wagons being farmed out. Seems that the wagons didn't get the "Fisher Body" sill plates because they were made by another body company.
Exactly what he was saying, the sill plates and trim items say Voila on them. I really don't want to have to have a custom headliner made... can you say cha-ching$$$
patience my dear man, patience, a classic car bought in haste often is a waste of garage space. That and I need to go actually look at it before I hand over a check. I'll be good seeing this monster on the road with first a Nailhead then Turbo6 power!