Untold numbers of antique engines got along just fine with the road draft tube ventilating system. They also were lucky to run 50K miles between re-ring jobs due to abrasive wear from ingesting dirty, unfiltered air. One of the positive results of the Clean Air Act of 1968 (entirely unintended , BTW) was an approximate doubling of engine life from using filtered air to ventilate the crankcase, and also purging acid-producing blowby fumes at idle and low vehicle speeds. Do it right, and a PCV system is a definite plus. If you're willing to keep a close watch on the oil level, put the PCV in a location where it can suck up liquid oil, and keep your valve guides well-lubed in the process!
Jerry
