I believe the only country who can trust pak or vice versa is US for its own reasons. No doubt these birds are flawless and having them in your fleet would definately form a formidable combination. Few facts before we think that it can harm us any way: 1) Sukhoi 30 MKI, and MIG35 is something India has in its arm which is equal to these birds. 2) Even pak purchases all these, it will have to depend fully on US for support and maintenence, for which Pak already cries.
And in todays AGE Pak would not like to attack on India in any case rather would try to intimidate us.