Resetting a 67 distribution block ?

[Daddy Brim]

I have 67 C-20 a while ago I had front brake failure, broke rubber line. since then I have replaced all rubber lines, calipers, shoes, and springs. I'm trying to bleed the system and it appears that I have all of the air out, not seeing any air bubbles when I open the bleeder. It appears the amount of fluid coming out the back is more than the front. There is no brake peddle, and I wound doubt it is the master cylinder as everything was fine before brake line broke. I have tried to do some research some say the distribution block needs to be reset others there is nothing to reset. What do I need to do to fix these brakes? I'm at my wits end. This is the distribution block that is in my truck.