I ordered an original carpet set for my 280sl from the dealer back in the mid '90s. I waited 4-6 weeks for them to ship from Germany and still was missing 2 pieces but luckily I got the driver's floor piece with the part number on it. I don't think the factory has offered the original sets since about that time.
I have since "searched the world" for those last two matching pieces and got samples from all of the sources I could locate. I found that the supplier with the most original materials was Klaus Herman Mayer in Stuttgart (
www.cabrio.de). In the US, GAHH seems to have the best materials available.
You have an advantage in that you have the original for a pattern. I would get samples and determine which matches the original best and then buy a few yards of that material and take it to a local upholstery shop and have them cut it and bind it as the original was and also install your original snaps. They shoulod also be able to find a heel pad that would be similar to the original. You would then only be missing the part numbers, but unfortunately I don't think they are available any more.