I need to clarify what I want to achieve. I want to get the same line spacing I used to have with mobi, but using the nicer fonts and style of azw3. I've tried all manner of settings (line spacing=0, minimum line height=0) but could not get the same effect for all azw3 books I have tried.
The only thing that seems to work is to set my line spacing to small in the kindle itself, but it would be really tiresome to keep switching line spacing settings when I shift from book to book, which I do all the time.
I guess what I am hoping for are some settings that would be ideal for converting to azw3 that would achieve the above-mentioned effects (smaller line spacing and regular-sized fonts.
I found that disabling font size rescaling usually leads to disaster when converting from epub. Most books I've tried to convert ended up having super small text sizes, so I guess it's font size rescaling or bust.
Would really appreciate some good guidelines from the epub to azw3 conversion experts.