You are going to need to bleed the master. it probably has an airlock between the m/c and the block. The prop valve wont switch back until it senses brake pressure on the rear. Sometimes they will switch back if you bleed the opposite end(front in your case), you may even have to loosen the front bleeder and pump the brakes a couple times with it open. then start fromscratch bleeding.
Did you happen to install a new master cylinder? If so it may need to be bench bled. According to what i understand in the shop manual, even if the proportioning valve has operated you should still have fluid coming thru it. I could be wrong though sometimes free advice is worth what you pay.
John and Tim,
I did bench bleed the master, I decided to take apart one of the old rear wheal cylinder. It was nealy dry in side. rusty but only a couple drops came out. I think I'm going to crall underneath it and cheak out the lines and maby open up the rear line over the rear axle to see if I can get fluid out there.
I had the same problem with the GTE that I pulled out of 20 years storage in a barn. The long brake line from the distribution block to the rear axle flex hose was blocked with rust, I had to replace it to get fluid flow to the rear brakes.