Krillin vs Kami
This is Kami in a human body at the end of Dragon Ball, against Krillin from the same time period.
Never seen this one before.
The way Krillin impressed Piccolo, who was evil at the time, I'm starting to think he may have pulled ahead of the humans by end of DB, let alone been strongest as of the Buu saga.
Who wins?
Piccolo hit him with everything he had, though. Hard enough where he was certain he overdid it and killed him, disqualifying himself.
And Krillin not only didn't die, he got back up, though in no shape to continue.
Between that and being fast enough to actually keep Piccolo on his toes (And more importantly, impress him, which is a pretty good sign of how strong Krillin really was), I think he'd do a lot better then Yamcha did. It should be an actual fight.
Another thing: Kami couldn't have been much stronger then Piccolo's father, if at all. And, his human body was a handicap..
Personally, I think the humans could almost certainly have fought King Piccolo post tournament training, given how power scaling works (Think Tenshinhan vs an amped Tao Pie Pie, and how Roshi was also able to keep up with Ten when he used to be at the level Goku was at when he was defeated by Tao..)