The road is in bad condition. At places it is mettled and then for tens of miles it is a dust track. At places it is very narrow and you might have to get offroad to let oncoming trucks pass.
You will also have to be aware that the direction of traffic in lanes is opposite from Iran. All through europe and turkey and iran you have LHD cars and in pakistan you have to remember going back to the RHD mode. Take your time and don't push the overtaking as others on road are not the most courteous drivers in the world. The only danger you face is from other pakistanis on the same road. Otherwise it is safe. You should be carrying plenty of food, bottled water, coolant etc because of summer. I am guessing diesel is easier to find than petrol.
I am with you on doing it alone without a worry even in a suzuki alto. With family, takes a bit of planning. But we did it as kids and teens a number of times with whole family. Tourists do it without any language. So it is doable. Take your time and plenty of pics and it will be adventure of a lifetime.