I'm 260ish now.
Hung off Dynaglide in my more bloated days - pushing 280.
There are a couple 300+ pounders hanging off Dynaglide now.
Moral of the story - Dynaglide is rated at 1000 lbs. 7/64 Amsteel is rated at 1,600 lbs.
Chart below from Knotty I believe (whomever this chart is from, feel free to chime in as I saw this ages ago and saved it in my documents) -
As long as he is hanging at a 5 degree angle or greater he should be fine.