17 volumes. That's amazing. If it was in the middle, I would have given it a chance like Bleach, but it was the ending. It's a no-no.
Honestly this is how I would've done it when it comes to the war, in total it'll be 9 volumes long.
Volumes 55-57 = The Beginning of The War
- Have the Ninja Alliance do their thing against various enemies
- Kakashi vs Zabuza rematch which leads into The Seven Ninja Swordsmen (Show the full fight instead of skipping it)
- Sakura vs Edo Tensei Chiyo
- Neji vs Hizashi (his father)
- Team 10 Vs Asuma (liked that one so we'll keep it) which would go into Kakuzu rematch
- Naruto leaves for the battle field
Volumes 58-60 = The Middle of War
- Naruto and Killer Bee encounter Itachi and Nagato (Another good fight)
- Suigetsu and Jugo break out of Prison and fight off against Kimmimaro
- Kabuto brings back Madara Uchiha and Fight Against Kage
- Itachi finds Kabuto and fights off against him solo and ultimately goes out stopping the Edo Tensei except for Madara
- Naruto and Killer vs Tobi and The Jinchuriki Begins
Volume 61-63 = Conclusion of The War
- Naruto and Bee vs Tobi and The Jinchuriki with Guy and Kakashi joining
- Kurama and Naruto put their differences aside once and for all then enter Bijuu Mode
- Tobi's mask breaks who is revealed to be Obito.
- Cue in Flashback at the end of 61 up to beginning of Volume 63 behind Obito doing all of this.
- Obito and Madara loose their respective battles and retreat.
- The War ends everyone celebrates and then arc ends with Sasuke removing the bandage and awakens his EMS.
I feel like there should've been more stuff I could've added but ideallly I think 9 Volumes is good enough to last the war.