Wow, a double-barrel TLF? That must be some 'new' design of carburettor created after everyone else was using fuel injection.
I think you'll probably have to make something fit. Perhaps the foam-type air cleaners have an aluminium baseplate in which you can cut some holes with a sheet metal nibbler.
Personally I don't think it's worthwhile to replace the standard airbox unless you have fitted a different camshaft or done some other mod that would require more airflow (like, a turbocharger... )
-Alex