As I understand it, the PCV system creates a flow of air thru the engine. There
is an inlet (usually from after the air filter) that allows filtered air to enter the valve
cover, and an outlet controlled by the PCV valve. Thus the interior of the engine is
"flushed" of blowby fumes by a more or less continuous flow of air.
As you outlined above, at idle when the manifold pressure is low and production of
fumes is also low, the PCV valve restricts total flow. When manifold pressure is high
and fume production is high, the valve opens to allow a much higher extraction rate.
Because it is impossible for a simple valve to exactly follow the rate of blowby fume
production, the amount of clean air drawn into the engine will also vary. In extreme
cases, if the PCV valve cannot keep up with fume production (worn engine) some
fume may be forced back up the fresh air intake and into the intake manifold.
So while you could create a PCV system for your engine, simply using a catchcan
and routing the discharge from the catchcan thru the filter backplate, would be a
simpler system to implement. The end result is effectively the same, and there is
less chance of creating tuning problems.
As some wise man once said... "just because something can
be done, doesn't mean
that it should