I talked to the previous owner about this car. Did you know that all of the control units were missing? When he told me that, I ran! I can't imagine how much all of the throttle, engine, traction,DM and BM modules would cost.
I would fix the engine myself. You CAN"T hone the bottom end. I'd bet there is little wear on the cylinders. They usually held up very well. You might want to do the rings and all other things related to the timing chain slippage though.
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS