Well, the best thing to do find what bloodline you want to know about (There are ALOT!!!!!!!!!!!) then do a search on it and read some of the post. Unfortunately you wont find an "All knowing" page that list the bloodlines and where they are from/how they were started. Just start with easy popular ones, if you like bullies look into Razors Edge, Gotti, Whopper, just to name a few, if its more "gamier" pits then look into perhaps Colby(must know this one!!), Jeep, Jocko, Sorrels...and the list goes on for both.
As far as South African kennels, if they are true APBT
then they will eventually go back to American bloodlines. Sure some people in SA might have started their "own bloodline", but if you go back far enough you will get back to the US dogs. Unless they were crossed at some point with SA dogs.