1) is your large pot proportionally bigger than 80 lbs of shrimp as your smaller pot is bigger than 20lbs? Because if not, adding the shrimp will cool that water more and affect your cook time.
sorry, that was a mistype. 60lbs. i am doing like 60lbs. we have like 40 or so people, but there will be plenty of other food.
i have a 120 quart pot, i usually do 70 lbs of crawfish easily in it with potatoes and corn, etc. i don't think 60 lbs of shrimp should be a problem. i have an 80 quart pot, thats what i used to boil the 20lbs in, but it is way bigger than what i really need for 20lbs..