Product: Uncle Mike's K/L Round (No Logo) Square Conversion
S&W carries Uncle Mike's K/L round to square conversion, which fits my hands fairly well.
The grips on the SSR are essentially a type of conversion grip; I suppose they would sell you a set?
I use the Pachmayr Pro Gripper on my range K/L revolvers for IDPA/USPSA. These are not really a conversion grip, and leave a small gap at the bottom back of the grip. Since the grips are rubber, there is no danger of cutting your hand or breaking off the corner of the grip. Can't feel the gap when holding in firing position.
Still, if you're more about looks than performance, this grip might not suit you.
You said you were aware of the Hogue grips:
All Square Butt revolver frames have been replaced by Smith & Wesson with Round Butts. Traditionally round butt guns were more cancealable and demanded a smaller grip. Now days it's common to put a full size grip on a full size Round Butt Revolver. Round Butt frames, being small, allow larger "square" butt-style grips to be used as pictured. The one piece Monogrip design makes an ideal grip for converting the round butt frame configuration to a square butt grip. The Hogue "Conversion Grip" allows a superior transition between the grip and the frame. This perfect transition is simply not possible with a two piece grip.