Trigger Coil Gap

Is there an old version of the MMH that explains trigger coil gap adjustment for old coils? Current section 24-20-00, pg 18, says new coils have elongated holes for adjustment, but it’s unclear how to increase the gap if holes are not elongated.  Or can I just file 0.010” off the holes to make my own elongation?!  Doubtful if flywheel hub can be loosened or removed without engine removal.  TIA