I have been a mechanic since 1976 when I went to work at a Chevy dealer after getting out of votech school. Was changing a lot of 307 chevy cams, most high mileage failures. Having been threw tech school I was taught the proper break-in procedures, the other flat rate techs laughed at me for wasting time. At that time techs just throwed the cams in and run them out the door, and you know what no major issues. They just changed the oil, no worries about metal still in the engines, no special break-in oils, just slam them together and go. Maybe a bunch of factors coming together, but I just believe flat tappet cams are such a small market today the quality is just not there no matter what oils or procedures you use. Times have just changed, if you want a vintage muscle engine, just upgrade to roller lifters, nobody can see you done it, no worry about always adding special oils, not really affected by sitting long periods, the extra money is well worth the peace of mind.