I believe there is a recommended independant shop list working on a seperate forum.
My suggestion would be to call someone you trust and ask them who they would recommend to do this work.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique