As you can see, the Pakistanis have no strategic depth. 
In my view, the Indian army would concentrate its armor in the southern plains of Pakistan. The northern, hilly and mountainous region, containing Islamabad, would be siezed by Indian Mechanized Rifle divisions or regular infantry while the armor rolled south.
The Indians would attempt to locate the Pakistani nuclear warhead stockpile (such as it is) and sieze it with airborne troops (India's equivalent of the SAS, I suspect). They would hope against hope that they could sieze as many mobile missiles as possible, but I doubt that they could succeed against determined Pakistani resistance.
My take is that India would advance to the Indus River and hold, investing Islamabad and forcing the Government to retreat to Karachi or Quetta in the highlands. India hopes at that time to dictate terms. Methinks, however, that they are in for a big, terrible surprise.
Be Seeing You,
Chris