I've been getting most of my MB-specific tools from this place:
http://stores.ebay.com/EL-PASO-TOOL
Picked up both the pre-combustion chamber retaining ring tool ($87) and the tool to pull and seat the chamber ($35). Very nice quality and fair pricing. I had originally made my own tool for the retaining ring, but with four of these engines to care for now I figured it best to have the proper tools.