Optimizing PvP Squad

I have a question on how I can optimize my PvP team. I currently float from rank 250 to 500. I have 7* Fives, Chewbacca, Luminara, Old Daka, and Savage Oppress with squad power of 31841 (all at Gear VIII working toward Gear IX). I like Fives because of the double attack, Chewy for the CC, Old Daka for CC and rev, Savage just to have a third tank and good DPS, and Luminara for second heal since Old Daka is squishy. However I have all the shards for 7* for Bariss, Sidious, Eoth Koth, Mace, Talia, Jedi Consular, and Ventress. I'm also farming for 7* IG-88, Boba Fett. And currently working on the Ewok Elder 6*. I'm a F2P but I would say i'm not doing too bad. But I would really appreciate if anyone would give me advice on my current PvP team(Besides getting to gear IX) and who should I trade out for who or what characters to focus on farming and advice would help though. Thanks