Make a smoother grayscale all the way from 0 to 255 and label the grays so you can find them.

Then take spotmeter readings and LOOK for where the spotmeter says they are one-stop-apart.

Those will be your printout steps. That's fine. Print a new target with the full stop steps you found. You might only really get 4 or 5 full stops of meter reading differences from White to Black. Probably best you can do with a reflective target.

I think that's the mental block you are running up against right now. The rest will come easy.