I've done hundreds of struts and I've always used an impact gun. No body I've work with has ever torque that nut to spec. Never had a problem
ETA: I should probably state that I use a 1/2 inch air gun with tons of torque, it doesn't allow the strut to have a chance to spin free. And I don't go crazy with it, just a quick "snug" should be all it takes.