Ignoring the contract, and just looking in terms of game, Dalembert should be a pretty nice fit--he doesn't really hog the ball and thus would allow for the furthering of JT's offensive development, and he fits that athletic/long shotblocker that he haven't seen since the days of Keon Clark. He's averaged 2.0 blocks for his career, and like Clark, has had his work ethic questioned despite being such a athletic defensive presence--if he's able to rebound and block shots well despite putting 50-60% effort, then even at that effort, he's still a more than serviceable NBA player. He's not a standout individual or team defender, but he's good on both ends. Offensively, he'll force passes and show his inability to handle the ball, but garners many dunks, finishes well and shows some short-range ability--that's the extent of it. Wouldn't be a bad option, and certainly better than Okafor
As for Giddens, he's just a great all-around athlete--lacking a bit of height, but super long and a run-and-jump athlete. He actually plays bigger than his body--he's a very capable rebounder, very good finisher and surprisingly a very good shotblocker for someone 6'5ish. He's lacking in his jumper though--his three point shot and mid-range shot are heavy concerns, although he's shown slight potential in this area. I'd prefer Bill Walker, but any athlete out of Boston's youth corps would be fine