I've had good luck finding CAD-cut seat foam backs and bottoms, based on application vehicle (so you know it fits), from an Amazon seller called The Seat Shop. I don't really know anything about the business (where, #, etc) but I bet they have contact info somewhere so you can call and ask if they can do it. Reasonable $$ for what you're getting, too.
Here's a search to them:
https://www.amazon.com/s?k=%22the+se...f=nb_sb_noss_2
(No connection to me. I just like them.)