Best of luck with the rebuild. The only comment I have is the valve to valve guide clearance should be in the mercedes intended ballpark. The oil flow up on that head is quite heavy compared to a lot of other engines. Plus it keeps your valve rubbers functional longer. I think mercedes clearance requirements are tighter than most. Plus of course on average valve grinding machine gives a better job without sloppy guides. I do not have the recommended clearances on the valve stems to guide figures. One of the on site manuals should have them. Skinner?