New classic car style bench seats?

I don't know of much else out there that fits what you want, that you haven't already found. But, a good upholstery guy can make the seat as soft or firm as you want it, add bolsters, and modify and sew a stock cover to fit..also not cheap, but a solid frame and your imagination is all they should need. The other option is to hit the junkyards, maybe there's something in a late model something-or-other that will work, that just needs maybe a basic re-cover job.