Hi Pedro,
Got your message and here is a useful quote for you from another forum member from Lisbon...I will send his email to you via personal message. I can also help you to understand some of the technical issues being explained e.g. removing shims in the WRD, etc.
"Hi Peter,
I had a bad experience with the Mercedes Classic Center, near Lisbon.
Then I met some people who recommended Ludgero Carreira, who has a shop in Mafra (60km from Lisbon).
He restored my entire car and did a fantastic job, plus he is an excellent person.
Old fashion shop, one old school mechanic, does a lot in house and knows who does the rest.
He used to repair / restore other cars, but recently focused is Mercedes.
When you come to Lisbon, we can arrange for a short visit.
Cheers
Francisco"