Just replacing the rings and doing valve job strikes me as entirely kosher if bores aint deeply scored. Look for soft metal Swedish aftermarket rings designed for high mileage ring replacement without cuttin into bores.

Piston slap and bottom end crank bearings going south on Mercedes is practically unheard of. Unless the engine has been abused, taken off road 20 yrs, driven overheated long time, run out of oil etc.