1. When installing, did you properly set the star adjusters per the service manual?

Rears are properly seated and adjusted. We had also gotten a firm pedal before we went soft.

2. have you removed the rear drums and made sure the cups and actuators for the rear wheel cylinders are still in their bores, and the star wheel adjusters still in place on the correct sides?

I havent taken the rear drums off again to check the actuators. I can double check this to make sure. The adjusters are on right also.

3. it might be a good idea to pull the drums and take a look and see if there is any seepage from the front wheel cylinders, since it appears you may have issues with this circuit now.
With as much fluid as we have ran through this car I cant imagine that we would have a leak and not see a huge puddle under it. The underside of the car is clean and dry as a whistle

I can go through and re-check all these items to make sure. Any other thoughts so I can add them onto the list of things to check?