A PCV valve correctly plumbed simply uses the manifold vacuum to counter any crankcase pressures that exist. Your compression ratio really doesn't enter into it, other than potentially leading to the crankcase pressures being higher due to more leakage. As long as your engine is pulling vacuum a PCV system will tend to balance the pressures, and the PC Valve will check off at speed, should manifold pressure exceed crankcase pressure, holding them balanced. Just my $0.02.