If we were seriously going win now mode? So leaving behind the fact that it's an awful idea, I'd say you'd need to figure out a formula to beat Miami and Indiana. No sense in a win-now mode that just gets you by Atlanta and Chicago. Teams that have had the best success against Miami have had really big, powerful front-courts to take advantage of Miami's one weakness. JV's potential doesn't count in win-now, and Johnson and Hansborough aren't elite. So you do whatever you can to get a powerful post presence at both ends of the court. Several of those guys on eastern-conference teams that are potentially out of the playoffs. Perimeter play is a big part of both those teams, so an upgrade to perimeter defense would be a big plus, but those guys are hard to find right now. I think you move out either Gay or DeRozan (probably DD), promote one of Ross or Fields to starter, hope that gives you an upgrade in perimeter defense, and then bring in an upgraded post player. You can also move one of the other bigs, plus any draft picks to make it work (yeah, I'd never actually trade our first-rounders, but playing along with the win now theory...).
Something around DeRozan for Al Jefferson (if Charlotte changes their mind about winning now, which wouldn't surprise me, and Kidd-Gilchrist and DeRozan could compliment one another so I could see them doing it). Moving out DeRozan would free up shot attempts for Jefferson and other players, and Jefferson has the flexibility to play PF alongside JV or C alongside Johnson, who can give you a solid 15-9 and defend well. And then an upgrade to backup PG, too. If you could trade either Fields or Ross for an established 3-and-D guy (probably needing to throw in a draft pick to make it happen), you do it, but I just can't see any of guys on the market who fill the role better than the guys we already have. In the short term, you feed JV and Ross minutes in hopes that they can grow as much as possible between now and the playoffs.
So a lineup something like:
Jefferson - JV
Amir - Hansborough
Gay - Novak
Fields - Ross
Lowry - Ridnour
Sooo, yeah still not a championship team, but I think that could be a realistic 3rd in the east roster, with an outside chance of knocking off either of the top two teams. I actually like that roster's chances against Miami more than against Indiana.
edit: oh yeah, and get a coach who won't try to beat Miami by going smallball.