All these numbers are just theoretical, of course. Who really knows their mineral content to a ppm accuracy??
But, my last IPA was:
120 SO4 - 50 Cl
With gypsum additions, at this point, my Ca = 102
I think another question should be, "How do you raise your SO4 way up without moving the Ca (gypsum) or Mg (epsom) needle too far"? Or, can you even raise the Ca and Mg needle too far? Yeah, I've read the water knowledge section in Bru'n Water and I know the recommended limits, but I don't take those limits as cast iron rules.