4 pumps, 1 saggin like a tit full O milk

Make sure you have fully bled the air out of your lines, as air in the line will do that.... Air can compress (causing the sag).... you may need longer strokes out back, possibly more weight.... Chaining the rear end will give you a bigger three also.

I have 10's in my rear, not long enough to stand a good three. I'm going with 14's, its a perfect size on a coilover. We tried 12's on my friends 63 with coilovers, powerballs, etc. and 4batts in each corner , and when just standing it only pulled front tire 12" up, were not satisfied with that, but the rolling i would have to say was incredible, it dragged back bumper with front tire 3 feet up in da air. go bigger, good luck.

if i put 12's on the rear will i have to modify the brake lines????

no you wont homie, just unbolt the brake block from the pumpkin, and lift it a little, be careful not to go to far, you might snap the lines if you do.