I know they would be a hard item to find, but perhaps Ron Sharp in Dunnville Ontario can help you.
I really like the Ithaca LAPD wedge type rearsight, (for the Ithaca M37 Deersalyer Police Special) and the front site is a triangle/pyramid of the same reddish/orangy colored plastic. The Ray-bar front sight, instead of a shotgun bead, this material is shaped with a tapered point for fine aiming.
The rearsight is a patridge type rearsight, just like a Colt Python or S&W Model 14!
There is no rear adjustment for windage or elevation, but at slug-gun slug ranges, who cares?
If you really want to grind out long shots, get a rifle, or learn your front sight elevation, just like Elmer Kieth did 50 years ago.
By the way, I have only seen these mounted on the normal 4 shot model DSPS, seems every 7 shot, extended magazine model, (DSPS)I have seen used the 'regular' rearsight, but the same thin triangle Raybar material for the front sight. This regular rear leaf sight, appears much like what you would see on a Winchester or Marlin lever rifle.
It's serviceable indeed, but not the 'foolproof' rugged construction of the LAPD type, designed for street engagements in the city.