1974 K5 Brake booster ? working or not?
 

I changed my master cylinder and bled the system. With engine off the pedal is hard .....with engine running it is soft and if I keep pushing it goes all the way to floor !!!!! Is this normal??? looks like i will have to test drive...........
I had looked at the fluid level and left the top off and got fluid all over the booster.........could I have ruined the rubber inside???

Sounds like the booster is working like it's supposed to, but you either have a bad master cylinder or air in the brake system.