I think too that Uvo is too much especially in a closed space. But in a lot of places (reedit, NF etc) people said that Knukle can beat Uvo easy, and that Uvo is just a mindless beast. I think people understimate Kurapika when he killed Uvo. I saw people saying that Chimera Arc Gon > Kurapika and Knuckle > CA Gon so Knuckle >> Kurapika and so Knuckle >>> Uvo....
About the match up I think in a closed space Knuckle will be stomped. The guy is strong and all but his fighting style his heavily CQC reliant and against someone like Uvo things will go south quickly. If he can't run away Uvo will give him back the interest and more and Knuckle will be hurt.
In an open space Knuckle can maybe do it, but don't really know. Knuckle is quite smart and he is not afraid at all to run away, and his speed is no joke too. I think he can try a tactic to hit Uvo once and play hide and seek with him till he goes bankrupt.
But Uvo can fight too, and one punch will hurt Knuckle a lot. And Uvo has experience and can make some tactics too. He won't do nothing and let himself being beaten.
And without Nen Knuckle can beat Uvo just fine. Uvo his strong but Knuckle with his strength and aura can likely beat him easy. To be with or without nen is a great difference.