Ya see, thats the point, theres always (Someone) something to point and ***** about. Perhaps, he used what he had on hand at the time? Perhaps you would like to donate a set of heads and pay the dyno guy.
Or better yet, build 2 383's yourself and dyno the 2 different heads! Come on now, you got money!
They didn't go into the build much. Just simply live with it. Good Lord man!