Master Cylinder Bleed Question

[JamesDean]

Lets say I have my master cylinder (500E with 500E booster) installed in the car...my 93 190E.

I hook up a master cylinder bleed kit. The kit has clear lines so I can see air bubbles.

I have someone pump the brakes in the car.

The line closest to the brake booster (side output) sees fluid movement first. A few pumps and the air bubbles are gone. I can still see fluid movement as my buddy pumps the pedal.

The line furthest away from the brake booster (top output), I don't see fluid movement until my buddy gets to >75% pedal position and it takes a good amount of pumps to clear air out.

My questions:
1) Which line supplies the front caliper pair? I suspect front calipers are on the top output line.

2) Why does it take >75% brake pedal travel to make the top output push fluid? This does not seem right to me. What adjustments or changes can be made to rectify this?

Looking forward to thoughts on this...