Hello leaf :
Just a question, how bad is the rear sight on this 99 of yours ?, is the sight base itself damaged ?. Can you show us a photo of the damage ?.
If the base itself is not damaged you can replace the rear sight leaf assembly by removing the pivot pin and installing a replacement leaf, the spring can also be replaced without taking the base out. Only if the base has been cut down does it need to come out and that would save you from having to remove the frony sight.