Guys, thanks for the advice. I'll go for the shop recommended by my mechanic since they've been doing MB for the last 20 years.

I just have a followup question. Since I'm left with the engine block, how do I clean off the gunk on top of the pistons. Parts of the residue has started to cake and wont come off easily. Is there a product on the market that dissolves this kind of residue?

I read somewhere that this kind of carbon build on the piston top may contribute to burnt valves.