Win the title next year team.
Marc Gasol
Kevin Love
Paul Pierce
Avery Bradley
Marcus Smart
Bench Thomas, Zeller, Sully, Kelly, Turner, Young, Hollis- Jefferson
Not possible. Can't have Thomas and Bradley while adding Gasol and Love. One of Thomas and Bradley needs to be dumped for cap space. Seems the most likely would be Bradley for a draft pick. As far as I know, teams were only offering late 1sts for Bradley... which is what it would take to dump Wallace. So you would essentially dump Bradley + Wallace for nothing.
Lots of threads here have us giving up Bradley for picks in the 10-14 range, but thus far we have no reason to believe a team is willing to give up a pick in the 10-14 range for Bradley.
That roster is 100% possible to create in terms of salary. There are two likely ways:
Love or Gasol is signed outright.
Then, a 3-way trade is worked out between Boston, Philly/Orlando/Denver/some other team without playoff ambitions next year, and Cleveland/Memphis. Philly gets #28 this year (Boston probably chose it for them on draft night) and maybe a 2016 2nd. They also get Pressey and Babb as immediately waivable salary filler. Cleveland/Memphis gets one of Olynyk/Sully/Zeller (probably Olynyk since he's under control longer) and a 1st (I think the lesser of the C's pick or the Dallas pick next year, or maybe this year's first if Memphis/Cleveland likes the player). Both teams also get a huge trade exception ($17 million for Cleveland, $19 million for Memphis, since they can absorb Olynyk/Sully/Zeller with a different TPE). This allows Boston to send out enough salary to match the incoming salary of Love/Gasol in a trade.
Alternatively, one of Olynyk/Sully is sent somewhere at a discount (maybe with Wallace lessening the draft compensation owed, or maybe not). Turner is also sent away. This creates enough room to sign both outright. Pierce is signed with the Room Exception (obviously giving Boston a discount to return, albeit not a huge one relative to the Taxpayer Mid-Level he'd get from the Clippers). The existence of this alternative (as well as Love telling Cleveland that he's signing with Boston or LA and that Cleveland has no chance) is why the three-trade scenario works, as it gives Boston enough leverage to not have to pay through the nose in the sign-and-trade, as there's a viable alternative that leaves Cleveland or Memphis high and dry.
If your preferred center is Jordan (as mine is due to Jordan's superior defense and stellar health record relative to Gasol), you can sub in the Clippers for Memphis in the above, and it works just the same.
But it is very possible to sign both max players without giving up too much in future draft picks or young assets currently on the roster --especially young assets that won't lose their roles with the signing of Love and a max center.
The biggest obstacle to the C's getting two max free agents here is finding two max free agents choosing to come here. Creating the salary room without gutting the roster is the easy part. In fact, it was easy enough that if the 3-way sign-and-trade scenario worked above, Bradley, Turner, and a pick(s) could be sent to Milwaukee in a sign-and-trade for Middleton.
P.S. All the above scenarios work with us keeping Crowder, although likely saying goodbye to both Bass and Jerebko (but possibly keeping one).