White Lum/Black Lum ratios?

Are there any loose ratio guidelines out there for LCDS?
I’ve been trying to get my NEC 20wmgx2 to get brightness settings correct, but its been tough.
My colors after calibration look good.
my brightness/contrast is off.

I work in a dark room and try and set my white lums around 100, but dont know where to put the black lums.

It depends on your monitor to a great extent of course. I have a cheap LCD in the office that can only get down to about .30 cd/m2. A nice Eizo on the other hand can get to .08.

If you are in a dark room, a luminance of 100 might be too bright.