I Wouldn't say he would dominate this Welterweight division, but I think he would prove to be the best Welter of the current era.
At his best he creams most of them. Like I mean gives sadistic, drawn out beatings some may never recover from. Guys like Pac, Crawford and Spence would certainly hang. I don't think Errol would be in with a sniff at all though. A fight with Porter would be gruelling..the ref would have his work cut out.
The 15 round experience and old-school grit would only be matched by Crawford and Pac for me, some fights he would have with them two....
Emile Griffith in his prime reminded me of a middleweight Floyd Patterson in some ways. Both were quick, both were counter punchers, and both lacked size. They were good fighters to compete with the greats in their respective eras. A Spence vs Griffith fight would be interesting, both respecting the others boxing abilities. A match against Bud Crawford would make fr a very close fight. Manny vs Emile would also be very exciting bout, both warriors would exchange speedy punches. The only big knock on Emile was that he was kayoed in round 1, by Ruben Hurricane Carter, in 1963.