Mopar performance valve covers?

I have the Mopar Performance valve covers on my Dart. They are on 360 heads. They may have been previously milled because they have a tight seal. Mine is set up with a PCV/breather combo (single inlet) from the passenger side. That valve cover also has the baffle installed. The driver side has a twist-on Mopar breather cap that I use as the oil fill location. Neither cover has been otherwise drilled out.