If i put longer shackles on the truck that will lift it right? What like a half inch for every inch longer shackle?

That's the basic theroy. You do need to consider on the front suspension, that the longer the shackle the more the pinion points toward the ground. Great for caster, bad for u-joint/driveline angle.

With that in mind... wouldnt longer rear shackles help with pinion angle?