Rear sight should be easy to find as it is the current rear sight being used on all N and L frame revolvers. Brownells, Midway,gunparts.com and Smith&Wesson will have it.

Problem will be figuring out what size and height of blade to go with based on the specs of the front sight used.

The front sight is going to be harder-it was only used on performance center revolvers like yours.

Best bet is to contact Smith Wesson about both.