I guess the OP should have refrained from using “break in” in his text, even tho title says “run in”. As others have said, breaking in cams, timing, valve and carb adjustments are much easier, not to mention any kind of leaks. And there is nothing sweeter than having someone spend half a day installing their engine in a car, then firing it up in a couple of cranks and having a nice smooth running engine immediately. The older I get, the less time I’d like to spend fixing something in a full bodied car, that could have been much easier on the stand. The references to break in procedures are interesting tho. Just my thoughts.