Forgot to mention, with 767 steps in code (1023-256) and 200 grams max weight,
you would get 200/767 = 0.26 grams per step.
To calibrate, you would need to use a 200g weight, then adjust gain for maximum code. If your zero gram reading is at 256, then the formula to calculate any weight from 0-200g would be ((code reading - 256)/767)*200 grams.