I thought I might be able to help you guys understand the valves that are in Camaros from the factory so that you know what has to be removed or replaced when doing a disc brake conversion. I used to do a lot of restoration work on Camaros & used to rebuild or restore these valves/ master cylinders.
Residue valve- these were built into the brake line ports in the master cylinder. When you remove the brass fitting there is a spring with a duct bill that held pressure. These were more commonly found when a car had disc/ drum from the factory.
Metering valve- This valve was used in cars when it had disc/drum brake systems. It was located on the side of the master cylinder & was plumbed to the port on the front brakes. Its function was to delay the front brakes for a couple of seconds to let the rear drums catch up to the front when you stepped on the pedal.
Shuttle Valve/distribution block- This valve was used as a distribution block to union all brake lines @ master cylinder & route fluid to front & rear. It also severed as a shuttle valve, when you lost front or rear brakes, the valve would move & allow to retain front or rear brakes & the brake light would turn on in the dash. It was a back up for the tandem master cylinder.
Proportioning valve- This block was located on the driver side frame rail. The valve would regulate the pressure to the rear brakes.
I remove all these valves when doing a brake conversion but rebuild the distribution block & reuse it if I don't want to replumb the car to keep cost down.