According to my 67 book, you install all the parts, and WHILE TURNING THE TIRE or brake drum, you tighten the nut to 70 inch pounds Then you install the castle over the nut, such that one slot is lined up with the cotter-key hole in the spindle. Then you back the nut off so that the castle rotates back ONE slot.
I do this slightly different, I like to "snug" the bearing up FIRST just to be sure that everything is "in" and then back off and retighten to the lighter torque. It is IMPORTANT not to either over or under tighten these bearings.