Disc Brake conversion power master cylinder question

Mine didn’t have the plug you have. I think that is a manual brake master cylinder.

I bought a power brake master cylinder that has a shallow bore, so I don’t need the plug now.

I am still having issues.

The pedal goes all the way to the floor with the master cylinder off. The booster appears to respond to the entire length of pedal travel.

However, with the MC installed and the brakes bled, the pedal only has a few inches of travel. The car stops, but you can’t lock up the brakes. The pedal feels like it hits a mechanical stop, like there is a brick under it. Very puzzled. Still investigating.

How far along are you?