The 6.5 JDJ has an amazing reputation on deer sized animals and the 6.5/270 JDJ beats it by over 10% in velocity.

It should serve you very well. I have had excellent results with the 120 gr. Speer on deer and antelope in my 6.5 JDJ.

Since you mentioned the 120 NBT, I will share this: Several of my antelope hunters used the 120 gr. Nosler Ballistic Tip in the 6.5 JDJ and nicknamed that bullet the "Ballistic Bomb." lol