Okafor has almost no value because of his contract and his decline (whether it's a decline in skill or a decline because of the team he's on is a matter of debate).
The question is what Celtics on multi-year deals the Wiz value. Green and Terry or Green and Lee work money wise. I'd do Green and Terry in a nanosecond, just to get out from under their contracts.
I prefer Okafur as well. my only concern is that in order to get him, he'd cost at least Green who I think Danny would need to move in a separate deal to get another (better) player. Okafur, IMHO, would definitely help this team but I don't think he puts them over the top. C's need more consistency from the bench as a whole.
If Danny can move JET, Lee, Bass and Green and add a legit center, backup PG/SG and solid wingman that's what he really needs to do. preferably without moving Rondo, PP, KG or the young players Avery, Sully or even Melo. A healthy wilcox and Collins should be able to backup at the Center and even PF positions. The big trick is if Danny can pull that off.