I used 2- 12" long pieces of 3" C channel and 2 large metal clamps and a quick clamp to hold it together while I got the screw clamps on.  It worked good.  Clamped this way and tacked, then removed, rotated 90 degrees, re clamped and tacked again.
 
Once tacked together, I put everything back together to make sure I was able to get the C clips back in and the brakes on, with the shafts.  
 
Sean, kudo's to you for doing all this work on your own & fabbing things along the way! 
 I've got a rearend that going to get cut for big Ford bearing ends and a Trutrac. The shop utilizes this product to make sure all is aligned.
https://www.mittlerbros.com/rear-end...l?options=cart
Anyway, keep up your good work, look forward to the updates.
Simon