It’s patented 
I guess this should be not in intake vacuum, but in the vicinity of oil pump suction pipe.
Else - use Tesla one-way valve setup ?
IF the crankcase is ventilated already, it should already have a slight vacuum.
Unless piston rings are worn …
That sure is a neat looking job, but I doubt it could be original
Would it have an adverse affect on engine performance if the small metal vent tube was plumbed via a restriction (such as a fuel filter) to the inlet manifold vacuum ?