2 P42DC are quite enough, the ATSF needed only 6000hp on their Super Chief and it was typically longer than today's Southwest Chief. The reason why we have extra loks is for Head-End Power, or for transfers throughout the system.
I doubt you have hotel power needs in India, thus it is easier to treat it more like a freight train on an accelerated schedule. If I sound brash, its just that I don't have any other way to put it.