If bought as a pack of livers with attached hearts, you need 350g for 200g net livers.
Use food-safe disposable gloves to handle the meat, if you're averse to touching slimy textures. I use
THESE - U.S. option
HERE).
The best way to ensure accurate measurement of ingredients is with Metric Kitchen Scales. They are inexpensive and take up very little space. Click
HERE for the ones I use. For U.S. option click
HERE.