garmin 1000 doesn't help for the 320.
these machines are heavy, 120T for the A320.
it doesn't matter if you come from standard instrument or garmin 1000 to fly glass cockpit. you will get 40-80 sim training in a level D sim anyway.
companies want 500h or more just to not pay extra insurance. the rest they don't care where you come from, what plane you have flown in the past.... all they want, is you don't cost them too much, or not at all.