Update: got the leaking manifold packing/gasket fixed. Turns out that the gasket I had previously used (metal sheet coated with graphite) is suitable for exhaust gasket, which had badly leaked and was damaged due to water flow. Irshad suggested me to go to Qadri gasket maker and I got made another allolite sheet thick gasket. Also got hylomar from adenwalla and used it to seal.
Besides, although Irshad himself suggested to get the manifold faced, but Malik saheb checked and said that it's fine and just rubbed it with a sandpaper a few times.
The heater valve seals (since heater is not connected atm) were also leaking and we replaced that too.
Irshad charged me pkr1000 as his labor which is quite reasonable for a 2 hour labor job.
I am yet to test the car on a long drive to see if there's any further leakage