Helen, thank you for such a detailed response!
I am a tinkerer too. This time though, i decided to find out whether there was something that could be done quickly. And if not, than how much effort would be needed to actually understand how kindle handles monosize fonts. For example, regular browsers ignore your direct attempts to set font size for <pre> tag.
I am sure that there there are or at some point will be some ways to influence conversion. But using AZW3 works well enough (ideally i'd like to have monosize fonts yet another point smaller) so i will not spend any more time on this.
Thanks again anyway