You are going to need a special jig for drilling/taping the block. The bolts don't thread in perpendicular to the face of the block. I believe the jig runs about 500$ here in the US.
I know Ashenmacher sells a kit w/ the correct drill bit/tap and MB has the correct heli coils.

Jonathan

__________________
Blue Ridge Mercedes
Jonathan Hodgman
http://www.blueridgemb.com/
Enthusiast Service, Restoration & Tuning.
Follow Us on Facebook!
Located in the Atlanta area
Specializing in all pre and post merger AMG's including Hammers and DOHC M117 engines.
Mercedes Repair Atlanta