At 147lbs Pac will win by either KO/TKO in the late rounds. Chinny Quintana schooled him and he isn't half the fighter of Pacquiao. Williams easily eats as much punishment as Margarito but doesn't possess the same chin or punching power as Margo so this is an easy pick despite the huge size disparity.
He has plenty chin to deal with Pac. Pac has a shot if Williams gives up his height but if he doesn't Pac doesn't win this one.
Williams is the most overrated piece of **** in boxing, he throws shots from across the street and doesn't even fight behind his height, he just throws tons of punches w/ no skill...bt to answer your question I'll have 2 give it 2 the guy w/ more skill, which is Pacquiao, I think he KO's Willians at 147 look at what quintana did 2 him and Pacquiao is a much better fighter