If you choose to plug that vent, be sure there's another way for air to get into the engine like a vented oil filler cap, or slots in the valve cover, etc. It doesn't matter if there's a PCV valve or a road draft tube, there needs to be some way for fresh air to get into the engine.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!