yep it does exist, here's one custom made too... another from Mopar Performance {photo from Mancini Racing MP-P5153738 $510.95} has the same spacing, linkage, air cleaner, element & carbs used as the 440-6bbl.... never available in factory equipped cars, like you said... there was a company that makes an EFI version too, off the MP manifold, F&B Throttle Bodies, if they are still in business....
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I think you could get the "rat roaster cross-ram base" {that had a removeable top like the STR's like example below for the wedges, with a 6bbl/six-pack top too, I remember seeing one, can't remember if it was a prototype or custom top or not, but I do know they were/are out there...