generally ya need about 70 to 80% pressure to the front if you whack em on hard. otherwise 60 to 70% normally. i'm guessing you dont want the latter. otherwise you wouldnt have upgraded.
if you want 70/30, f/r... 30 is less than half the pressure of 70. (obviously)
so if as you say, 100% on the front, you'd be looking at about 35% on the rear.