Tarver is the opposite I think, a right hander fighting southpaw! A few Left handers that fight orthodox are: Barrera ( I think, could be wrong) Kessler Cooney Pavlik is ambidextrous (I think) I once read Frazier was left handed too, not sure about that though?
Chad Dawson is right-handed but fights southpaw too. His dad was a southpaw so he wanted to emulate him.
I have a friend who's really into the local boxing scene here in the Philippines and he said we have a lot of naturally right handed boxers who fight southpaw because of they have a tendency to put their strong arm forward (i guess from instinct?) or closer to their opponent and end up in a southpaw position. And because we have a lack of really good trainers, this often goes uncorrected for a lot of boxers. I don't know if he was just pulling my leg but it's interesting if true. Don't know if this applies with Pac but I know he writes with is right hand and he plays darts with his right hand (if you remember the Pac Hatton 24/7). Still, I find it hard to believe that someone with such a devastating straight left would be right handed.
That one hurt. I was also stricken impotent for six straight hours afterward. I mean-......I had...some...uh...I had a headache for six straight hours afterward. Amen to that.