Since hub treads are standardized (pretty much), any freewheel can be substituted as a unit. However, there is virtually zero cross compatibility between freewheel sprockets and bodies. There will even be compatibility issues within brands, ie. Perfect sprockets mostly don't fit Winner bodies.
As I see it, you need to buy any freewheel, or fined a used Perfect freewheel of any size and transfer your sprockets onto it. I wouldn't go the transfer sprockets route, unless I had a non-replaceable freewheel size range in near new condition since it's the sprockets that wear not (usually) the bodies.
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