Aluminum stamped valve covers
I'm just putting this out here for info. I know its not exactly what you are asking for.
I have Mancini aluminim valve covers on mine. they have one hole at the front and one at the back. both have baffles under the holes. on one side I have an Edelbrock breather element pushed into a Mr. Gasket baffled grommet. so that side is double baffled. on the other side, I actually still use a pcv valve even though it is a race car. however, I run the hose to a air/oil seperator mounted on the firewall, and then to the rear of the carb from there. I still get the scavaging effect, but I eliminate the oil mist from coming back into the intake charge.
I have zero oil getting by either side. like I said, I'm just throwing that out there for info if anyone can use it.