Micheal ;
Firstly , any Mechanic will tell you , the engine pic you posted shows a vastly cleaner engine than usualy comes into the shop under it's own power....
The Dealer sells individual piston ring sets .
Deves Piston Rings in So. Cal. (? El Segundo ?) alsop makes and sells rings for anything ~ anything at all .
Cheaply too .
The carpets look nice and unworn , only dirty , why not clean 'em ? .
You're doing a good thing here and will LOVE this car when finished .
Keep up on the detailed notes with pix as it'll encourage others to follow suit , too many perfectly good Mercedes are being sent to the crusher these days for under $500.00 .