While the physical arrangement can vary for different engines, the PCV Valve should always be connected to the vacuum source. In other words, between the vacuum source and the crankcase.
If the PCV valve is mounted in the valve cover, a hose connects it to the intake manifold or most likely a large vacuum port on the base of the carb.
Fresh, clean air flows from the Air Cleaner, into a valve cover, through the crankcase, out the other valve cover, through the PCV Valve and into the intake manifold to be burned.
A valve cover breather can be used on the fresh air side of the system, but those breathers are generally cleaned every 20 years. Taking the fresh air from the air cleaner, benefits from the air filter being replaced on a more frequent basis.
PCV valves are made in many configurations. You just need to make sure air can flow through yours in the proper direction.
