We all agree that Perk is gone for part of the season, but there's no consensus that he'll be shopped. So given the possibilities of that and Sheed retiring, I'd say sign Shaq and draft a big. Here's why
Shaq starts in place of Perk so he can learn the system and get in shape. BBD picks up Sheeds minutes and our draft pick(Dexter Pittman or whoever) works 5-8 mpg at PF/C. Then halfway into the season, Perk returns to start and now Shaq could be in shape and now our system and our draft guy would have had enough time to shine or stutter.
Come playoffs, Shaq turns into this years Sheed and shows up for us. Also having a great passer like Shaq in the paint, Rondo can get more layups and Nate might get a dunk in