Why don't you use the standard method of pack control by using trim air valves to mix hot air into the air conditioning pack flow outlet to the flight deck. With this system which are usually present on large aircrafts, you have a pack setting which is standard and the trim air valves which...
Just to add a little info on this topic of Emirates and Qatar buying Airbus's, Qatar has obviously opted to stick to Airbus and thats also the way Emirates started out. They only had 2 Boeing 727's initially which they got rid off earlier on. Emirates has actually ordered about 26 Boeing...
