The reason I keep bringing up pinion angle is, you have leaf spring in your car, when you put the rear end under load the pinion wants to rotate up, and it DOES, from the factory they new this, sooo they tilt the pinion down as much as 7-8 degrees.
On a ladder bar car the pinion cant rise, if you weld your bars to your housing the way it is. your pinion could have a 7-8 degree angle(not good for U-joints or ET's). you will have some adjustment on the rod ends but you dont have adustable links on the bottom bar which will make it a pain in the a**.
This is why I keep saying... put the front of the ladder bar in the middle hole with 0-1 degree pinion angle at ride height. This way, if you move the front of the bar down (which increases your pinion angle) you will have room on the rear joints to to adjust to 0-1degree pinion angle. Viceversa if you raise the front of the bars.
Raising or lowering the rear of the car also changes your pinion angle.
http://www.carcraft.com/howto/91758/index.html
This might help you understand what I'm trying to get across.
Good luck,
cam67152