Excellent. Do you also do this sort of thing “for fun”? If so I may have questions for you in the future, so I hope you stick around even when your current project is complete 
If you’d like / be happy for your filter to be made generally available, you may be interested in having a look at this topic about suggested guidelines for Audacity Nyquist plug-ins: Conventions for Nyquist Plug-ins
If you’d prefer to just post the ‘raw’ filter code that’s fine (though it would be helpful if you could explicitly state if you intend it to be GPL v2 compatible)
What an excellent resource - thanks.