Not being a 220 pound man abusing alcohol for 20 year, I can't speak with authority.
However both of my parents, almost nightly, drank themselves into oblivion, and Dad was about 195 lb.
While Mom took to the vodka bottle, Dad limited himself to Rob Roys which are essentially two shots of booze.
I never kept a log on his consumption, but my estimation is that he downed at least eight before he fell asleep on the couch.
For the purpose of your tale, one bottle of whiskey should do.