Need help with brakes on frame off restoration

[Jerblazer72]

Everyone,
I am nearing completion of my 3 year frame off restoration project. 72 GMC LWB 4wd. I need to get brake fluid back into it and need help. I rebuilt the brakes, drained all fluid etc. Now I need to get them working. I have been reading for a couple hours and still am not sure exactly what to do. I have tried to gravity fill/bleed them and the fluid is not going out of the master cylinder. I am not really sure what to do from here. A key thing I noted from some of my reading was that the little pin on the front of the proportioning valve must me pressed in when gravity bleeding. My pin seems to be in all the way already, it does not move in or out from what I can tell. I do know that it worked correctly before I began the restoration. I was thinking of just starting at the pass rear and bleed them as normal until I get fluid down there ad proceed as normal. Any thoughts or suggestions will be greatly appreciated (especially by my wife who has to deal with me when I get frustrated like this)!