I'd do the Cousins trade. I think Roy's is probably pretty similar so I will go with that one.
1. Celtics trade Brown, Zeller, Young, 2018 Nets pick for DeMarcus Cousins, Omri Casspi
2. Next acquire Noel for Rozier, MIN 2nd, LAC 2nd. I think that is comparable value.
3. PJ Tucker for Jerekbo, CLE 2nd, DET 19 2nd, MIA 20 2nd
4. KJ McDaniels for Cash (fit into trade exception)
So post-trades
PG - Thomas, Smart, Jackson
SG - Bradley, Green, McDaniels
SF - Crowder, Tucker, Casspi
PF - Cousins, Olynyk, Mickey
C - Horford, Noel, Johnson