re: "...What type of oil did your rebuilder recommend for teh break in and for how long?..."

Actually, I never asked the long-block builder -- he shipped it empty, anyway.

But I had a good talk with my MB dealership's service mgr. (he's a cool guy who appreciates stuff like what we did on my G), both about oil and breaking in the engine. His advice was to NOT use synthetic (I always use this in my cars -- and my boat) for at least 8-10,000 miles. He said that whereas new MB's come with synthetics, their blocks' cylinder walls have special alloy coatings, and have been prepared to very close tolerances -- they don't need to be broken in; while my engine, without the benefits of modern alloys, should be given a traditional break-in period.

He also said that the best break-in technique would be for me to drive it NORMALLY. Don't baby it, don't keep the revs low, etc. Only, don't do any full throttle starts and keep it revved to the red-line, either. Just drive it with some enthusiasm (he knows me ;-), but nothing extreme.