you need to understand reason for 1971 wasnt unavailability of PAF but unavailability of detection system till it was too late, secondly Pakistan was outnumbered far more than what it is today especially on eastern front
PN needs to get assests upgraded to early detection and PAF would need to back it up with its assets, each thunder can easily perform a 2X2X2X1 configuration with stand off range of 250KMs, so as soon as its up from Karachi, it can let go its arsenal for any threatening vessel way before it even reaches Pakistani waters, IF IT CAN BE DETECTED AND TRACED VIA LONG RANGE SURVEILLANCE SYSTEMS
i would take a jf-17 self escorted in above configuration rather than expensive JH-7, the long range detection will be possible with AWECS(400+ range for detection)
what PN and PAF need is excercises for strong co ordination, and what PAF needs is support from PN and pak army to expand its fleet rather than duplication of same arsenal, this will decrease cost..we have chief of joint staff for same reason which for example isnt a post in india where you see an odd duplication of same system which will mean more cost..something depsite what people say we cannot afford
look at bengaldesh with almost same econmy as us and than us and compare our arsenal