I've had good luck using IKAR brand points that I've found on ebay. I guess they were the vintage points brand sold for Mercedes cars back in the day. Made in West Germany, really good quality if you can find the ones that fit for your distributor. The ones I bought are ventilated (they have a hole where the points make contact with each other).
This is just a random link that I found on ebay searching today, don't know whether they fit your application or not, but IKAR is a good brand. Search and ye shall find...
Vintage Mercedes Ignition Points, 000 158 35 90
WWW.EBAY.COM
Only fits certain years and models, double check this is the correct set of points.