Good find Dinger. There is a lot of misinformation out there.
I just broke in my freshly build flat tappet small block chevy using Brad Penn SAE30 break in oil. It was a bit pricey at ~$7/qrt but that is much cheaper than the repair bill on rebuilding a 2nd time!
For the 500mi break in oil I have Meijer brand (yes the department store!) conventional 10w40 which, for now, is SL rated oil. For piece of mind I replaced a qrt with Risline ZDDP oil additive.
AMSOIL makes a synthetic oil with the required zddp levels called Z-ROD that I may use after the 500mi break in. It's $10+qrt though. Comes in 10w30 & 20w50 varieties.