The only one among them I'm familiar with is Mackenyu, who is a solid actor. If you're worried if he can pull off Zoro, watch Rurouni Kenshin: Final where he plays Enishi, and Over Drive in which he plays a talented racer named Naozumi, who's workout scenes scream Zoro.
The others look the part, for the most part, but I know little of them. They could be good. Now all we need is casting for the rest.