We'd need to trade Horford and Griffin has to give up about 3 million to the max to make it work, but it would be the best team that I can think of that would be somewhat realistically possible and would be worth it to build it as an instant contender and main challenger of the Warriors. We'd be able to keep the core intact for a number of years.
PG: Isaiah Thomas, Terry Rozier, rookie
SG: Avery Bradley, Markelle Fultz, Gerald Green
SF: Paul George, Jaylen Brown, Abdel Nader
PF: Blake Griffin, free agent (MLE), Jonas Jerebko
C: Brook Lopez, Ante Zizic, Thomas Bryant
Main rotation for the playoffs:
PG: Thomas (36), Fultz (12)
SG: Bradley (32), Fultz (16)
SF: George (20), Brown (28)
PF: Griffin (32), George (16)
C: Lopez (32), Zizic (16)