I accidentally ingested 7g of paracetamol/acetominophen in combo with hydrocodone when I first started using drugs. I thought apap was something else. It caused me to get sick and vomit multiple times. Opiates never make me vomit on their own, so I am pretty sure it was the paracetamol.
It doesn't really matter what the LD50 of a substance is when it comes to recreational drug use. You don't want to go anywhere near that level. Using large amounts of paracetamol will damage the liver. I would not use the max daily dose of 4g more than occasionally.
It's not very hard to extract most of the paracetamol. It is not very soluble in ice cold water. I think it's as simple as crushing the desired number of pills, mixing with a small amount of cold water, putting in the freezer for a few minutes, sucking the water layer from the top, and squeezing the liquid from the mush. The water must be cold, it is more soluble in warm water. The more water you use, the more acetominophen will be in it. I don't know what max ratio of water to pills can be used to make it safe, but the info is easy to find. This kind of extraction takes only a few minutes, surely you have that much time to spare.
Just search bluelight or the internet for codeine cold water extraction.