front disc brake conversion

So that entire kit was installed and the pedal goes to the floor?

I’d look for leaks, barring that it’s most likely air in the lines. Brakes need to be bled. Was the master cylinder bench bled?

Are the calipers installed so the bleed valves are on the top? Because they can be installed on the wrong sides, which puts the bleed valves on the bottom instead of the top.