Think around 215*- 225* is what Jim told me.
When Jim talks about "wallerin" the thighs ,lightly tented,in a bottle of sauce,he is slightly below that simmer level-or barely at it.
I have notes from when I tried them countless times,but I got away from those biggest ,self trimmed thighs ,that Jim liked to cut.
The little thighs may have been down around 200*,to take the 3 hrs.
If it is critical to you,I can probably find them,but your FEC may run a little different than my cooking.
His cookin' buddy, Fred,checks in here from Arkansas,and he might be more helpful.