IMHO, taking the car to a professional upholstery shop is he best way to go. This is not a DIY job and if you attempt it yourself, you will get DIY results which will look like crap. You won't get any dates, girls will notice the crap B pillar job and run away.

Check out the upholstery shop carefully, skills and experience vary. You want someone who has prior experience with vintage mercedes automobiles.