The data you are looking for does not exist. If you are going to build a cab then just use cardboard to make a couple of test control panels. You can figure out what works best for you.
Slagcoin.com has joystick and button positioning templates. That would be a good start.
First, let me thank you for the reply and for your advice. Yes, I know Slagcoin.con very well but as I wrote in my op post my goal is to gather data for statistics. Building a CP is in agenda, of course, but before that I have to sort out some sort of "research", so to speak.
To tell the truth, I expected that there was no database like the one I'm looking for...but all the same I can't help but find this fact quite disappointing: after more than 20 (30?) years of emulation and self-made cabinets nobody has ever thought (or wanted) to create a banal database where anyone can find valuable and essential info like these quickly and in a detailed and organized way. Yet a lot of people in all these years have invested tens, hundreds or thousands of hours of time to create software tools of all kinds, overlays, bezels, arcade art, etc. etc.
I mean, we have seen everything from the most incredible ideas to the most ingenious creations, both in cabinet building and emu-software development but in 2020 you still have to waste time searching among a thousand sites, google, hundreds of forum posts just to get info that in my opinion should/could have been made readily and clearly available for the masses long time ago. Just my opinion, though.