A potential problem with Super Sixing my 1973 Duster.

volaredon said
I have a housing from a "68-ish "Super 225" here that I'm probably going to do just this, sacrificing one of my many 318-2bbl air cleaners I have for the conversion.

That's not a Super Six. The Super 225 was a marketing name for the early 225 engines. They were not equipped with the 2 barrel carburetor.