The "yellowing" is most probably from the aged PEARL tint on the OEM white vinyl. The pearl tint was on all of the Chrysler trim codes up until the change for the 1974 models. It won't come off with cleaners. That's what gives the vinyl and cloth it's sheen, rather than just a normal color (as Ford and GM used), which is missing from the '74+ trim codes.
My '67 CE23 has the white pearl buckets. On one corner, it is dingy. Tried to clean it and it didn't change one iota. Then I realized it was the pearl that had changed and not the white under it.
I suspect that any paint you might find will be just the color itself, sans pearl tint.
I'd always like the way the Chrysler interior seat fabrics looked. When I went in search of some possibilities of new cloth for the '66 CL42, when it was about 7 years old, a trim shop owner said that none of the GM or Ford items would match the OEM Chrysler colors. Which is due to the pearl/metallic tint on the colors which Chrysler used. He put them side-by-side and it was very obvious. I was both surprised and pleased that I now knew why they looked better than similar Ford or GM interiors.
Just some thoughts,
CBODY67