Dose your peddle sink to the floor over time this is a sign of a leak internally inside the master cylinder. How thick are your pads? Maybe steel lines are the way to go I hear thy help. Brake peddle hight adjustment may help. Do you have rear drums some times adjusting the rear drums help.

Ya I'm running out of ideas the 4 ways I know how to bleed are pressure(use the pressure tank), vacuum (use a vacuum bleeder), gravity (open all the bleed screws) and pump the peddle (you know).

What are you thinking?? I'm out. Pressure bleed is usually my last resort.