Ok, I did do the search function, but didnt find anything that was dead on. I just did a power disk brake swap on my 68 chevelle as well as put new shoes, drums, and hardware on the rears. What seems to happen is when the car is off it'll have somewhat hard pedal, then when it's on it'll feel like it has no resistance at all till the last inch and then it'll stop good(tests up to 40 mph). I think I did a sub-par job bleeding the brakes(Gravity bleed without holding the prop. vlave button down(is it necessary?)) or the rears aren't adjusted right. Thanks for any replies.

A spongy pedal indicates air in the lines. If the pedal is solid, then the rears probably need adjusting. A hard pedal is normal with the engine off. The booster uses engine vacuum for the assist. Right after shutting off the engine, you should get one or two assisted applies before the pedal goes hard.

Well, It's not really a spongy pedal, cause it feels like theres no pressure at all on the pedal till the last inch, and then its solid.