Small, Chrome, Air Cleaner Lid -- ?

That type of housing was also used on the slant 6 with a different base plate (of course), but was semi-gloss black instead of chrome. If you can find one in decent shape, it may be cheaper to just have it chromed instead of paying crazy prices for a beat up original.
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As far as an aftermarket chrome air cleaner goes, the closest I have found is this one:
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United Pacific S1102 Air Cleaner Cover 11", Dome Style, Chrome | eBay
The overall dimensions are the same as the Commando/Charger unit, but the top is a bit different.