Hi barit1,
Was he merely lucky not to depart the regime of positive roll control, or did he have some insight beyond his seat-of-the-pants about how far to push the beast?
He could "push the beast's" rudder until he was about to run out of aileron control, which is easy to feel in a Boeing through the control wheel displacement.
If he were trying to do the same thing in an Airbus FBW - then he'd have to be looking at the Flight Control System Page to see how much aileron was being applied for him.