I take it you are talking about the ball joint stud hole in the rear knuckle.
You are replacing the pinch bolt each time with the new balljoint aren't you?
Don't over tighten the pinch bolt, as it will start to stretch , come loose and eventually break.
If that hole is slopped out that the pinch bolt won't keep it a tight fit, then it's time to replace the knuckle, modifying that piece is not worth risking your and everybody else's lives.
$150.00 for a new knuckle? Check the junk yards, or post in the mall that you are looking for a new (used) one.