I have a 10k mile engine and still get the film somewhat, but my covers aren't baffled and neither are the breather extensions. I have some stainless potscrubbers I was going to stick in there, though.
Does anyone know where you can buy the pcv stuff for a 289? On the passenger side valve cover all I have on the valve cover is a rubber plug. How does the pcv hook up to a Holley carburetor the correct way? Anyone have close up pictures?
Measure the large carb intake barb and take the valve cover plug with you to a decent parts store. They should be able to set you up with a pcv valve and hose to carb for less than $10. I would recommend the pcv setup to burn the blow by and assist in ring seal no matter the engine ring condition.
Remember that at wot there is almost 0 vacuum, so most blow by goes out one breather. Some blow by will find it's way to the baseplate, but will be restricted by the pcv valve and the small hose. One breather may not be big enough to vent all the blow by and actually have more crankcase pressure, causing less ring seal and more blow by. A few cars back had a pcv system and the filter had oil in it. My guess is that air must have been going out as blow by increased and only at idle/cruise there was enough vacuum to pull air through the crankcase.