Check the documents first. Everything should be complete. You should be able to get it's UK registration number if it was a used, UK import. If you are able to obtain it, check it's MOT history on the UK government's MOT website. It's free and very easy to do. Anyone can do it.
Check the tires; they should be relatively new. The e65 740li came with 19s as standard and tires cost around 150k rupees for all fours. Check if the car shows any errors on the dash. All parking sensors should be working. Check if there are any signs of leaks around the sunroof since the seals dry out and owners don't bother changing them. I've seen many e65s with leaky sunroofs in Pakistan. Check if the lights are clear; they should not be yellow-y or fuzzy. Check if all the seat adjustment functions work and ensure no button is missing (which they usually are if the car isn't taken care of).
I've seen lots of 7 series with faulty Logic 7 units. Check if the speakers work and don't hesitate to play a song with some bass. A new logic 7 unit costs around 350k from Dewan (cheaper if bought kabli). Check if the air conditioner blows cold air consistently and there is no excessive vibration when the cooling fan for the engine turns on. Check to see if the alternator is charging properly (should be at 13.5-14 when the car is running). Failing alternators are also very common. Check if the adjustable steering buttons function correctly. Check if the I-drive system (the infotainment unit) is laggy or not. Check for any vertical lines in the infotainment unit screen. Most 7 series in Pakistan have broken I-drive knobs from previous, botched repairs so be aware of that. Lots of 7 series have sagged roof liners at this stage and expect to pay upwards of over 80k for a proper Dewan job. Check to see if the suction doors and trunk work properly. They are a very expensive fix if anything goes wrong. All buttons in the interior should work.
When test driving it, check if the transmission shifts smoothly. If it vibrates/jolts when you slow down, walk away from the car. Transmission replacemet is very common and is NOT cheap. There should not be any oil leaks when the car is stationary. The car should not feel to wallow-y, but somewhat taut.
I would recommend taking an OBD-2 scanner along with you. Dewan charges approximately 8k for a pre-purchase inspection last time I checked.