Last Chapter - I hope!!
After all of the aforementioned stuff, i.e. adding prop valve, pressure bleeding, etc., I decided to double check a few things and started blocking off the rear brake lines just to see where the problem appeared. After messing around with the tee on the differential things got noticeably better. It apparently was holding a bubble. Brakes were still not where I wanted them so I took the ebrake style calipers off and tried standard GM calipers and I could get a good pedal after three pumps. I then wanted to try the ebrake calipers and see if I could get back to where I was with the standard calipers. I put them in the vise with the brake line hole up and carefully filled them with brake fluid all the while tapping. I took them out of the vise and covered the hole with my thumb and "swiveled" them around and got 2 -3 bubbles out of each one. When I mounted them I attached the brake line while inverted, I had clamped off the brake line and before I tightened the banjo nut I released the clamp and let the fluid flow and fill any voids. Anyway, I got to where the ebrakes calipers where as good as the standard calipers were so I added a 10lb residual valve and I have a good pedal.
I think the thing that made me chase my tail so long was the bubble in the tee - two problems, not one. I have some other things to do under the car but I will probably try the brakes next week.
THANKS to everyone that contributed.