Custom Springs

I was looking into springs for my 07 ms6 and have not really found anything I like (waaaay too much drop on most aftermarket options) besides autoexe and rpm sports. So, I was thinking about custom ordering some from a shop local. Does anybody have specs on what a good spring would be on our car? It'll be used for daily driving and maybe some autocross down the road, so I'm thinking 330lb/in front and 250 lb/in rear. They'll be going on bilstein b6's because I want similar to stock ride height. But what spring length would that end up being? also, what are stock springs Inner and outer diameters? and I've seen some pure rally cars on here discuss resonant frequency for the track but what would be a good resonant frequency for daily driven springs?

Thanks all!

 

@phate is your best bet for good info

 

Almost like phate made a huge thread just about this topic, man I wish people would search, read this thread should have the info you're after...

https://mazdaspeeds.org/index.php?threads/suspension-by-the-numbers-car-setup-how-to.1427/

 

Thanks, apparently, I didn't search well enough