I had really good results cleaning the original interior in my '37 Master coupe with Orvus Paste. This older post describes how to use it.
Cleaning Upholstery I used it for the seats, door panels, visors, and headliner. The results were impressive.
Tips to remember:
1) Be patient.
2) Use a damp wash rag to blot the foam on to the upholstery/cloth and gently wipe it.
3) Rinse by blotting it with another damp wash rag and rinse/wring that rag frequently in clean water.
By the way, I have a whole lot left over! I bet I did not use 10% of a 7 1/2 pound jar which is the smallest I could buy.
I will be glad to send you a couple of pounds. Send me a PM.