Doc, that's a real nice lookin' white bucket seat. Looked at the picture first before reading your post and thought right away, uh huh a mustang bucket. I've done foams and upholstery for a number of 64-66 mustangs and it sure did look familiar. Pretty bright white too, maybe you otta leave the plastic on to keep it clean.
My dear Grandma, bless her soul, bought a new set of easy chairs back in the '60s for her living room and think she left the plastic on them for 10 years. Grampa always liked to come in from the barn after his milking chores and sit down to read the paper in his easy chair. Grandma never had to worry about the upholstery gettin' soiled from Grampa's dirty coveralls.