This is the latest official rom for Lenovo P70-A international version with 2GB ram
Use TWRP recovery to flash this rom
1- Copy the rom to your internal phone storage
2- Turn off your phone
3- Press on VOL+ & Power till you get a screen with 3 Options
4- Choose recovery using the VOL+ key and VOL- to confirm
5- Press install and choose the rom zip file to flash from your internal phone storage
6- Wipe Data + Cache
7- Enjoy 
Please visit this link for TWRP Recovery & Root
http://www.needrom.com/download/lenovo-p70-a-p70-t-twrp-update/