The above pictures show the differences between the Monterey (top photo) and the Montclair (bottom photo). The interiors are completely different on these two 1956 Mercurys. This Post doesn't answer your question, but I thought that I would share these pictures.
SMS does embossed pattern door panels so they should get you there. They can also custom emboss seat vinyl coverings. That is one thing about the 50s & early 60s cars that made things difficult for auto trimmers and restorers. That stuff was not available for a long time.