If the engine was good running, with solid oil pressure instantly on start up, and during hot idle, you have good crankshaft bearings, and good rod bearings. So if that's the case, you can assume that's all good. Wet and dry compression tests will show condition of compression rings, but not oil control rings, as well as how well the valves are sealing against the head (if the wet compression number increases substantially, you know the compression rings are leaking air pressure).

If this were mine, I'd remove the head and ship it to Metric Motors in SoCal.... unless I had an amazing machine shop locally. I'd purchase a straight edge from the Snap-On tool guy and check my block for being straight, and if it was fine, I'd wait for the head to be finished. Head gaskets and valve cover gaskets, etc are readily available from all of the common online sources like auto haus az and rock auto.

I'm glad you're having a knowledgeable MB tech do the work. It's kind of a tough job due to the size and location of the head, and the timing chain situation can be dicey because it's easy to have the chain come off the fuel injection pump sprocket and knock the pump timing out of wack. So you think you have it all back together, and the engine won't start, or runs poorly, and you can't figure out why.....oops, lost the pump timing!

While you have it torn down, it wouldn't be a bad idea to replace the engine mounts (the right side takes the mount with the red dot of paint on it, because that's the version made with harder rubber. You can probably use 2 red-dot mount though. Replace that little front engine strut, down low, and consider replacing the transmission mount and it's boot. Also take a peek at the fuel injection pivot plates and their 3 bushings up on top of the intake manifold. There is one nylon bushing, out in the open, and 2 bronze bushings pressed into the pivot shaft area of each plate. These like to wear, and it creates a bunch of play, resulting in inaccurate timing between the throttle plate and the mechanical injection pump. If you have no play, great. But if there's play, a set of bushings, and resetting the linkage rods if needed, will actually improve the engine performance very noticeably. There's one more pivot point on that same side of the engine block. If that one is worn, you replace the pivot bolt, the metal bellcrank plate, and the bushings. All of this stuff is still currently available from Mercedes.

Looking forward to hearing about your progress.

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