Speedway Motors sells them. 22 1/2" tall, 15" deep, and 18" wide at the bottom, with or without upholstery. Economy seat for roadsters, dune buggies, and sports cars. Had a pair years ago in a Kellison.
I have an old fiberglass bucket from the eighties, I cut the headrest portion off, duct-taped some cardboard over the resulting hole, filled it with resin and glass, sanded it smooth, and pulled a mold. Bingo, an endless supply of low-back sixties fiberglass buckets for the cost of the glass. These things are all over the place for virtually nothing, as every one has put poly buckets in thier cars in the last few years.
Ya, as Cerberus pointed out, Speedway Motors has them. They call them their "Sportsman Fiberglass Seat". They are very resonable and can be bought with or without the upholstery. From your location, you could have these in your hands in one 1 to 2 days! No joke, I have been a customer for years. Go to speedwaymotors.com and pull up their streetrod catalog. ...Robber
Those seats are only 13" wide at the bottom. My buddy Joe just bought some for his AWB chevelle, speedway's dimensions are wrong.
Speedway was mentioned,also check out Summit or Jegs. Search a VW site or forum, may find some for cheap and used. Many ran them in dune buggies.
That last set from limeworks is really nice. Great buy with the covers and cool vintage looking covers.
Old thread, I know. Limeworks doesn't advertise them anymore. Has anyone tried aircraft seats? https://www.aircraftspruce.com/catalog/appages/bucketseats.php?clickkey=6739
Well I got a set of the Aircraft Spruce seats. 16" inside width, 16" deep and 21" high after you make your own brackets. They are 3.5 lbs each.