Ford experts.......HELP!

[GaBnn3]

I bought a pristine 1987 Thunderbird, with 12,000 miles, from a Ford collector. The brake proportioning valve began to leak and got worse until it had to be replaced. It's no longer available from Ford. So, I got the correct one from a salvage yard, and replaced it. When I tried to bleed the lines, I could do the front, but not the rear. There's no fluid to the rears. A friend, who's not familiar with Fords, told me that the valve has to be bled or primed, or I won't get fluid to the rear. Now, I've got no rear brakes. I don't have a factory service manual. My Haynes manual is no help. But, it says that they're factory pre-set, and don't try to adjust them. Can I do this myself? If so, how? Any help would be greatly appreciated. Thanks.