Good evening, my name is Walter.

Can you tell me more about the work you performed, like if you've simply replaced the master cylinder, or you've done other work in the process. Also, what prompted you to replace the master?

While you're offline, just to throw a few things at you, have you bench bled the new master cylinder? You could still have air in the system that you won't get out from bleeding the lines at the wheels. This video will give you a quick understanding of that:

Bench bleeding video

Also, do you have the shoes adjusted at the drums? If there's excessive clearance between the shoes and drums, it will take a lot more fluid to cause the shoes to reach, thereby giving you a low pedal.

What kind of fluid volume are you getting when you bleed? Once the air is out, it should be a good stream when you crack the screw. If not, it's possible you simply have a restricted system.

When you can get back with more details about the other work you may have performed, I'd be happy to discuss further.