Lantana, Since you have the engine on the stand while it's awaiting the transplant, here is what my buddy Mike at http://www.mercedesengines.net/ suggested... This may sound crazy to you as it did to me, but Mike is one of the biggest MB engine rebuilders on the west coast...

Drain all the oil and remove the oil filter. Fill the engine with Kingsford Charcoal Lighter Fluid (about 6 qts)... Re-seal the oil filter cap, remove the pin from your engine stand so it will rotate back and forth... swing the engine from side to side 45 degrees for a few minutes, making sure not to go much further than 45 degrees because you don't want the "CRAP" in the bottom of the engine to come into the cylinder walls... Do this like it was a washing machine cycle, back and forth...

Drain the oil pan again... You'll see some really messy CRAP come out of the engine... This is most of the sludge, varnish and metal patricles that have accumulated in the oil pan, pump, and flow channels...

Then, fill the engine again with Charcoal Lighter Fluid... But, this time over fill it with 2 qts more than your oil capacity or until you see the liquid at the base of the neck of the filter housing... Then let the engine sit on the stand for a week or so... This will allow the lighter fluid to seep into the cylinder walls, valve guides and valves to break apart the carbon and varnish build-up...

After a week or so, drain the fluid... When it's all out, put a few more quarts in and do the washing machine cycle again and drain it immediately... You should see fairly clear liquid by now, or something like weak coffee...

Then, while your engine is sitting and waiting for transplant, overfill the engine with oil by about 2 quarts, or until the oil is visible in the neck of the filter housing... This will help keep the moisture out and also re-oil all the walls...

PS: Drain the excess oil from the engine before you fire it up for the first time...