IanC,
Welcome to the Forum. I think it will be difficult for members to help with your value question without a lot more information. You might zero in on a ball park value by viewing sites like Hemmings, bringatrailer.com, Hagerty, etc., as well as following posts on this site regularly.
If you will look at the technical manual, third button from the left above, you will find a suppliers list. Here on the forum you will frequently see posts mentioning the most common suppliers for various parts. There is also your local Mercedes-Benz dealer and the MB Classic center.
You can find significant information on your car and components by using the main search function, fourth button from the left above. To become familiar with this site, you might want to read through a few threads under each of the major headings to get a feel for the kind of topics discussed and the diversity of information available. Reading your way through the Tecnical Manual sections is a long process but is also rewarding.
Good luck with your restoration. You might consider starting a thread to document what you are doing, what problems you have and how you are progressing. You are sure to get a lot of comments and help. Pictures are important and are always welcome.
Again welcome to the group.