I don't think of any of those guys as really being a post player. Of that list, I'd go with Rasho, who's big enough to provide depth at the C spot and who can help stretch the floor.
For a post presence, I'm wondering if they'll ask 'Sheed to play inside a little more than he has in recent years. He's [dang] good down low, he just tends to fall in love with his jumper a bit too much. We're still going to be mostly a shooting/slashing team, that's just how the roster is constructed for better or worse. Maybe they'll call Perk's number a little more, the work he's put in on his inside game seems to be paying off.