Melo to Boston doesn't make much sense to me, but what about Dallas? No state tax means Melo's dollars go further? Winning coach and owner.
Something like:
Matthews, Powell, Williams, Curry, 2017 1st, and 2019 1st
for
Melo and Rose
Cuban might be willing to pay the keep Rose, and under Carlisle's coaching, Rose might become relevant again. The Melo-Barnes-Dirk trio would be tough to guard. Not a championship team, but way more competitive.
The Knicks get a good look at Powell, who could be an interesting high skill dirty work player next to Zinger. Matthews can be a steady contributer and floor stretcher from the wing. Williams can fill in at point guard until they draft one or sign for one. Obviously, the Mavs picks could be really good too. Obviously they clean up their roster and move in a new direction with Zinger, while staying competitive and getting draft assets.