Hi Mark, difficult to say if new bolts (e.g. head bolts) are actually available from Mercedes. I would imagine, however, if they are they are likely to cost an arm and a leg. I have carried out two Valve Grind and De-coke jobs now just on at least ten years ago, and I can report that, to all intents and purposes, I have had no need to purchase replacement bolts. Whilst one of the cars is no longer in my possession, Gleaming Beauty the subject of one of the jobs, is still in my possession. Up to now, and as I said at least ten years (with plenty of pictorial evidence on TK published at the time), I have not had a single drop of oil or water as a result of the particular job.
I still have many head bolts for both the 6.3 and 6.9 M100 engines, but knowing which are which I am not able to differentiate. However, they are spares I have on hand. BTW, I see that you still have this car. I had been under the impression that you had sold it, but maybe I am missing something.......Regards Styria