Residual vavle

Do I need a residual valve to the rear? 1969 Camaro, I just did a front disk kit install on my camaro. Also replaced rear cylinders and rear flex line. Ive pressure bled two quarts of fluid through and not seeing any bubbles but pedal goes to floor. it will pump up and hold but if u release and let set it goes back to the floor. I dont think the master came with a built in residual for the rears. I read that a rubber piece would be in the rear MC outlet if the MC had the residual valve. I also dont believe the combo valve that came with the kit has a residual valve in it.