Again even the guys who buy and use the highest quality flat tappet cams are having trouble, look at this thread from class racer, these a stock eliminator guys using best parts available https://classracer.com/classforum/showthread.php?t=85341 the flat tappet camshaft is not a reliable piece to put into an engine anymore. The people that knew how to make them are either retired or dead in my opinion, the knowledge is lost. You can jump all the hoops with oils and break-in, but it is a crap shoot. I was a mechanic at a Chevy dealer in the 1970's nobody got excited about break-in on stock engines and special oils they just throwed them together and they worked. The only guys who broke-in cams were performance cams, and most of my buddies who installed smaller performance cams were oblivious to what break-in was and they still worked just fine.