setting the ride hight with air bags

[sqweaka]

hi all, ive installed 6" firestone airbags in a xjs front clip on my 49', because of the pivot point of the A arms on the jag clip ive 12" of lift from the floor to full lift... on the rear im installing a home built four link setup with firestone sleeve type bags which have a 6" lift but because they will be closer the the axle it will only lift by the 6"
the four links need to be set level at ride hight, question is what is the inflated hight i should set the rear bag at... if you see what i meen
if its got 6" of travel do i set it at 2 thirds of its travel to allow both up and down movement as you travel down the road