8 3/4 ?'s

best way is to put the perches on the installed leafs, set the axle housing on the perches (centered), put the U-bolts on, but don't torque them down...just snug, install the center section and the axles, no need for the brakes, and install the tires.

set the car on the ground, and you should (maybe need a jack under the pinion yoke) be able to rotate the housing to get the right angle.
then tack the perches in place on the housing (don't weld them solid or you might damage the springs), and remove everything again so you can weld the perches solid

i know it's a lot of work, but it's probably the best way to do it....