It's not kid Goku that he/she is talking about. He/She means the Goku after the training with King Kai in which he's got Kaioken.
Actually he went to King Kai after dying with Piccolo's special beam cannon. That killed Raditz as well.
I am talking about the time when Goku was fighting Raditz. If Goku gains Kaio-Ken, Dante would loose hands down.
A regular Kamehameha without Kaio-Ken is not that strong to destroy anything more than 5-6 buildings in line of fire.
By the way, I am female, so you can cut out the 'he/she' thing.