The seat cushion can be swapped with a passenger's side one. It's a bit of messing around with bolting and unbolting seat backs, mounting frames and brackets, etc, but it can work a treat - passenger side cushions are often not as worn as driver's side ones.
If you luck out with Spac in the search for seats, @pigdog may have one.
Then there's also this car on Facebook, which may have a good passenger's side one.
https://www.facebook.com/marketplace/item/559783677943985/
