Traxxas Slash motor choice question

OK, i've fall in love with this truck, and i want to put it brushless. I'll run my MM on 3s.
Please is somebody here could tell me which are the best motor for this truck (Kv rating)???

And if somebody have already one at home, can you tell me the exact lenght of the baterie box??

Because i've Thunder Power Extreme V2 5000 mAh, 3s, and it's on the long side, 150mm if i remember.

Thank you!