I took a look around the web and see what you mean about hard to find that 1:60 biplane, especially die cast. And I think the Corgi Barnstormers are 1:72 so probably too small - from my quick search.
I also tried 1:56 and 1:64 - the latter might work best if you can find anything, probably a more common scale. I could find biplanes but couldn't identify the scales. I'll keep my eyes and ears cued up for this - if I visit my local hobby shop I'll ask the proprietress, one of the most helpful people you could imagine, a legend for the quality of customer service she provides.
And if I've provided a small amount of inspiration it is only fitting considering how much I've taken from your work.