If conditions suit swing bowling and are comparable to the ones in Bellerive Oval where Philander was almost unplayable, than Sohail Khan should be first choice. He starts with 140 kphs and when he is tired and huffed and puffed he drops pace to low 130's... But as I remember from SA vs Aus Test match, Philander was constantly 125-130 during his spell and he is simply awesome.
Another very very important factor is Sohail Khan being right handed fast bowler, whose main weapon is outswing. In swinging conditions, most right handed batsmen are vulnerable against out swing bowling if its pitched on 4th-5th stump, and all lefties become lbw candidate as the same delivery becomes an in swinger against them. Having three left arm bowlers could become a liability for Pakistan in the end, as it was shown in England Tests...