I assume you are doing this job in leather? Recovering the dash pieces will require you to have the leather "skived" or made thinner than standard thickness. Gahh will do this but has limitations on their thickness. If you go vinyl, the vinyl stretches just enough to stretch it around the compound curves of the dash pieces.
I am working on and off on my interior. My car originally had dark brown (essentially black) leather. I wanted to go cheap (10 years ago) and ordered a replacement in cognac MB Tex (now for sale) thinking this would be easier for a novice to install. And it is not too hard to do. After peeling off all the leather and installing the MB tex which the supplier provided in sheet goods (not pre cut pieces), I have now decided to go back to leather. This time red. I am still challenged by what it will take to fit new leather on the dash pieces, instrument cover, hard door pockets, glove box, door handles, soft top compartment lid and the windshield trim. I got a name of an interior guy from John at German Auto Tops to do the leather installation on these pieces. He will take care of the skiving.
The next dilemma was the type of leather. I am not sure if people replacing their leather seats realize that the hides used today by most suppliers use a different dying process than Mercedes did back when the W113's were built. Today's leather commonly supplied for W113 interiors is vat dyed and the dye is through the leather. Original leather was vegetable dyed and just on the surface. When I compare the 2 samples, I can see, feel and smell a difference. For a premium, GAT will supply what they call Old-Timer leather.
In my case, I still have my old leather pieces. Before I install new leather (seat covers and door panels will be new) I am investigating dying my original leather and gluing it back on. This could potentially save me a couple thousand dollars. There are leather treatment products that claim this should be possible. I figure I have little to loose if I try. Besides, my old leather is already pre-fit to my pieces.
Matt. I have a question for you. Is your car automatic or standard shift? Are you planning to replace your carpet?