On my 66 C-60,when I got it,the brakes would pump up to about 3 or 4 inches off the floor with one pump,but never got any better,and I had to pump it up every time I used the brakes. I thought I would have to go through the brake hydraulics on it,but a friend and I decided to bleed them and see what we could get. We bled the right rear brake forst,and the pedal came up to where it should have been,and the brakes work fine now.
Try bleeding the brakes thoroughly before you start replacing parts. Work from the farthest fitting from the master cylinder to the closest.The brake booster will be the last one you bleed. BTW-even though there's no bleeder screw on your master cylinder,if you need to work air out of it,you can bleed it by opening the brake line right at the master cylinder just as you would a bleeder screw. Just be careful not to round the flats on the line nut.
