If your engine is built, and your engine builder recommends something, I'd go with him as well
I never said BITOG was perfect, its a community forum not an experts forum.
Re the Ford 6, I'm running 15w40 at the moment in a 1996 Ford Engine, I'm considering Penrite 15w50, the other choices were 10w60 (or 70 or something with really big numbers). Just looking for a cheap fully or at least semi-synthetic for the Ford as some of the cheaper oil gets burnt up pretty quickly.