Half Brakes or No Brakes

Hi Folks,

I have a rather large problem with the brakes on my '72 240z. I'm mostly finished with a resto/rebuild of a Scarab Kit 240z. I decided to replace the entire brake system with all new or N.O.S. parts. I have bled the system completely to remove all air, and even resorted to having a local garage power bleed the system for me. It appears that I still have minimal rear brakes. I only have half a pedal, and this diminishes when the engine is running. This is a completely stock brake system. I really need help with the following questions:

1. Are 7/8" Tokico and 7/8" Nabco stock Master Cylinders interchangeable?

2. What type of adjustments, if any, need to be made to my new vacuum

booster push rods?

3. Will a brake pressure switch from an early '77 280z work in the early '72

240z brake system? Does that switch also double as a proportioning valve?

Could this be the cause of the trouble?

4. How do I know if my rear proportioning valve is working? At this time, I

can rotate the rear wheels by hand if the brakes are applied.

Any help or advice you all can render would be greatly appreciated.

Thanks again,

Tony Russo