Silenttrouble

I got a C3 yesterday really cheap as a project car. I being 25 have never really done much work on the old style cars as I've been limited to new technology like EFI and newer ignition. However this C3 has a 454 in it. Not sure what it came out of because I am pretty sure the 75 c3 did not come with a 454. TO the point. *edit* Hopefully no one saw how stupid my first question was.... The big breather holes in the valve covers. One is tied to the vac system the other is just open to air. Has the rubber ring for a line to be inserted there is just nothing there. Is this a problem running the engine with nothing covering or filtering stuff that can get inside the valve cover? What should I put there?