I've long thought that Boston might be able to put together a decent package something like this, I think would work for both teams
Smith and Williams
for
Allen (1 yr, 6-7 million), Bass (3 yr, 20 million), and then any two (or three if absolutely necessary) of the following: Johnson, either player drafted this year, or a 2013 first (lottery protected)
I think Atlanta might prefer Green, but I'm not sure Boston has sign and trade rights with him (they have bird rights, but might not be able to sign and trade him based on the rule). If Boston can do a sign and trade for Green, put him instead of Allen.