I believe the best kit that will get you closest OOB (if you want to model an M4A3E8 vs. an M4A2E8) would be the Tasca M4A3E8 JGSDF Easy Eight: www.hlj.com/.../Mil
It has the rubber chevron tracks as opposed to the Tasca WW2 US M4A3E8 which has the all steel wartime T-66 tracks.
I don't think the Tasca M4A2 is even usable because it has the early direct vision hull and all the early fittings associated along with the early turret.
Do you want to make a true to the movie M4A2E8? You'd probably need to get the Dragon M4A2 PTO hull and add the Tasca JGSDF kit turret, tracks, suspension, etc. Academy also does a late hull M4A2 that you could bash as well.