It was interesting that on the cast iron 8l v10 Chrysler went with a fixed orifice instead of a rattle type PCV

Here s another variation

http://www.envalve.com/why.html

In theory
Having a low vacuum inside the block
During part throttle cruise
Would give a slight fuel economy benefit
... The backside of the piston would not be fighting against a pressure and internal moving parts would encounter "wind age" aerodynamic losses