Goro does have the 2.5x advantage in AP and Dura, and as long as Goro doesn't use a weapon, while Dowan is a decent brawler, he's never been trained in martial arts so he would get skill-gapped most of the time in hand-to-hand (unless he uses his unorthodox skills). Also, he has a mana limit of 4,000 and so some of his best abilities like Indom. Will (cost 500 mana), his dura-neg skill "Carving the Weak Spot" makes him have to use the skill first, place a "spot" on the opponent's body, and then hit that spot repeatedly (cost 1000 mana), and his 5x speed skill (booster is 300 mana) has a 30 second time limit, he can't use it with other skills, and once dispelled, has a 3 minute cooldown. Furthermore, while he does have shockwave creation, their not as easy to summon compared to Goro's projectile attacks, which will be very harmful against him.
(Also, not going to lie, some of the other candidates wash Dowan so he needs to get lucky with matchups too

. Kind of why I advocated for the Black Lock item use but will be fine if it's disallowed)
If that's still too much, I do have a backup from the same verse,
Choi Sunjae. He has the same AP, Dura, and LS as Dowan but none of the hax (besides a limited attack redirection). He also get's skill-gapped and while way stronger in-verse (he's basically the strongest in the series so far), he has none of the hax that would make dowan more threatening in matches. Though his speed technique has been shown to outpace Dowan's 5x booster through his disciple's usage so there is arguments he could get a 5x speed increase with his speed technique, it's not "official" yet either.