The 'custom' Barrel Rib and front Sight on this one, being modificaitons done probably fifty or sixty years ago, are none the less modifications, and, would ( to some degree ) put the Revolver at a lower value, than an example which is still in it's original configuration.
Can you post some more images? And some which show the details of the Front Sight and Rib?
Correct Stocks for this will tend to be hard to find, and, will be expensive if in good or fine condition, and they are a matter of luck and perseverance, to find.
ebay, Gunbroker, local Gun Shows, is where one would tend to find a pair. And the seller may or may not know what they fit, may or may not or describe them properly in the subject line of the auction. So, lots of looking is usually what it takes.
Nice custom Shooting Master! Would be nice to find out who did the modifications. Looks like hammer and possibly trigger was also done. Since the Shooting Master has been modified for target shooting, why not consider after some market target shooting grip options, such as Herrett's, or Roper-like or similar. Hmmm, round butt or square but under those Goodyears? No need to try for original grips - target stocks make more sense in this case, IMO. Jackson