As I'd previously noted, there was another potential credit for Oh Ji-hwan, but I wasn't sure on it. It took me a lot of coming back to and looking over my pics and footage again and again, until eventually I felt confident enough to make a decision. But I also held off for a bit then, because there was the possibility that he was playing several roles and I wanted to hold off until I was sure. Well, I can say for sure that he is in the film, but I could only be certain on the one role, maybe once a BluRay version comes out I can reappraise the situation. As I suspected, he was credited under a slightly different name: Oh Ji-man instea of Oh Ji-hwan, so I've updated his page to include the new aliases.
Duel Of The Tough [1981]
https://hkmdb.com/db/movies/view.mhtml?id=10304&display_set=eng
I also added Kang Moon-ho to the cast list, as this is his only other credit apart from Seven Men Of Kung Fu, in which the footage is so poor that it really doesn't help with an ID. I do have a theory of who he is in Duel Of The Tough and I've taken steps that may hopefully lead to a proper ID in the near future, so fingers crossed.
Cheers