Just picked up a 94 pickup sas with s12w calipers on all 4 corners.
truck has the 1" master cylinder to go with them as well.
spent a couple nights toying around with it trying to get a good pedal still no luck. swaped out the two front calipers one was sticky and one had a bad piston. LSPV is zip tied all the way up. My big question that i cant find much on is rotor thickness truck has vented rotors all around but they are two different thickness all rotors are almost new.

fronts are .790 thick 20mm
Rears are .875 thick little over 22mm

would a adjustable pressure regulator be helpful? running out of ideas here

 

I've never done this conversion. So here goes. The MC is moving a lot of fluid so for nothing to happen is bizarre. I think there is air in the MC so I would open the RF bleeder and put a hose into a can and try to bleed the system.

The rotor thickness should not matter unless the piston are coming too far out of the calipers. So I think you are Ok; there.

Do you have a buddy to help push the pedal? It might be air bound and a vacuum bleeder will help solve this problem.

 

finally found specs on the rotors. they are sized correctly rears are a little thick but just difference in brands i belive. thinking im gonna pull the lines off the MC and verify that it is pumping even though it should be brand new. then hooking up the pressure bleeder.

anouther side note ive checked every fitting on the truck twice and it has ss lines no mushy rubber. really shouldn't be this complicated their only brakes

 

If the brakes have never worked correct per chance are any of the calipers on upside down making it impossible to bleed correct??

All it takes is one connection that allows air to be drawn in

 

is the pedal too low, too hard to push, etc??