[Steeveedee]

That side is the gozinta for filtered air that the PCV system removes. I'd leave the arrestor inline, or optionally you could put a screen inside the air cleaner where that hose hooks up. Older vehicles used a simple screen. Check around in the '60-'66 forum, you should be able to find a pic. Just having a breather will potentially allow dust into that valve cover, depending on how dusty the conditions are. The spacer will ensure that the air cleaner housing clears the carburetor air horn. The air cleaner housing may clear anyway, you'll just have to check.