RR - I got lost in your description but the reply post is what I'd think would work.

You could certainly do it with an empty housing and jackstands under the axle to have it at running height so the springs would deflect the same way they would with wheels on the car. The pinion should be at right angles to the mounting flange on the axle housing, so there's a bit more difficulty setting it right, but on the other hand, welding on a bare housing should make positioning of the workpiece for maximum welder comfort, resulting in a better weld.

(I would have said deflect correctly, but my '64Dog has a stock rear spring setup with a considerable amount of rear steer built in, and I cannot get myself to call that spring arrangement correct.)

R.