Rocky Graziano fought around 154 a lot.....and had the power to deck SRR & Zale. But not better than Hearns.
Hurricane Carter was arguably a light middleweight :good I don't see Griffith having much of a case if you take into account fighters like Ray Robinson and the other greats who fought at around 154 lbs. Griffith wasn't the best ever at any weight, be it 147, 154 or 160, but he was one of the best, and that's an accomplishment in itself.