Thanks for sharing your historical work. It appears to be deeply thought out.
The manual goes on to name other feats of strength, such as ...
... and a ceremonial caldron weighing 1,000 catties (1,300 lbs). ...
... a reference to the Warlord Xiang Yu (项羽, 232–202 BCE) who is recorded to have lifted such a caldron in his youth.[28] The Purple Elixir Daoist did not need to mention these fictional and historical figures by name because they were deeply ingrained in the Chinese cultural memory....
[28] Peter Allan Lorge, Chinese Martial Arts: From Antiquity to the Twenty-First Century (New York, NY: Cambridge University Press, 2012), 61.
So, I have also found a reference to the story of lifting the cauldron. But, I have not been able to find the original source.
Do you have that handy?
This is illustration is circa 1795.