1974 C20 still have brake problem

[mntoy]

Never got my brakes fixed, I bench bleed my MC again, and leveled the truck and did it on the truck too. Back brakes bleed out great and stiff but the front brakes stll have lots of air, not sure why. I have bleed them manually by pushing the brake pedal and used a speedy bleed but lots of air keeps coming out even spurts large bubbles. When I go to fill the reservori small bubbles rise out of the front brake reservoir only(the one for the front brakes is what I mean). while the truck is off the pedal is great but when I start the truck pedal goes straight to the floor and does not come back up. What am I doing wrong, I have been through two quarts of brake fluid bleeding and it has not gotten any better. the brake light does not come on and I have tightened every fitting for the front brakes. Any help out there?