Yeah, honestly I don't think Jackie Chun is that close to the two finalists. Granted that Keme-Sen'nin stated he 'might' have lost to Tenshinhan, but he then was completely unwarare Goku was hiding a new level of power and seemed genuinely surprised by Tenshinhan's speed when this latter was attacking Goku. Considering that Tenshinhan seemed excited with Goku's existence stating he is happy there's someone who can pose a challenge to him, I think Kame-Sen'nin is just considerably weaker than him, which also falls in line with him admitting inferiority to Goku before knowing Goku had a new level of power.
Yajirobe on the other hand was the toughest person Goku has ever met, withstanding a beating of an angry Goku without any injures, plus there's even some additional lines in the anime implying he might have been a challenge to post 22nd Budokai Goku, like the one in which Goku stated things aren't gonna be easy against him besides stating he hit him as hard as he could.
So, I'd say Yajirobe has this fight without much problems, unless Roshi pulls off a Bankukki Bikkuri Shou or use the sleep hypnosis followed by a full power KMHMH.