Sorry, but you haven't really understood the map or the geometry involved.
The point of an S-400 to my eye would be dominate at high altitude over Islamabad so that the Indian Air Force could engage and destroy the Pakistani Air Force from a position of height advantage while protecting the New Delhi axis. If the PAF uses high alttitude tactics the S-400 destroys them. If they use low-level tactics to avoid the S-400 then the SU-30/A-77 destroys them from high altitude, or the S-400 will datalink via the A-50's or other 3rd party platforms to engage such targets.
So the three assumptions I made are that (1) the IAF has a significant combat advantage with the R-77 if the Pakistani air force is forced to fly lower; (2) the S-400's missiles can be deployed remotely = 100's of KM, say at Poonch - from the fire control radar and (3) that S-400 at 200km (Jammu to Islamabad) has no problems firing at targets, either directly or via datalink to 3rd party systems. Which of these is not correct?
The key assumption is that I'm assuming that if the Pakistani Air Force wants to fly low to avoid the S-400 at Jammu, then the SU-30's at 30,000 feet will have a field day, and if it flies high for good AMRAAM shots, then the S-400 will have a field day.
Edited by glenn239, 11 March 2019 - 0853 AM.