I don't buy into the idea that liver is dangerous for someone who doesn't have other deficiencies (particularly the other fat solubles). If you consider that a lamb (sheep less than 1 year old) yields 2 pounds of liver, then we would have had, in our somewhat recent Pleistocene past massive amounts of liver to consume or discard, the latter being highly unlikely. A modern day elephant's liver is 170 pounds. Were there human die-offs every time a mastodon or mammoth were killed? I imagine the aurochs, megatheres, elk, rhinoceroses etc. were yielding fairly substantial amounts of liver, that, even if split among a tribe are going to greatly exceed 100g a week.
There would almost certainly be times where particular individuals would have subsisted purely on liver. I think using the arctic explorer (who was very likely deficient in vitamin D) polar bear story to determine how much liver we should eat is misguided.
That all being said, I think a pound a week is completely safe.