If you can disassemble a S&W hand ejector, the swap is a cake walk. I swapped several and they have all been drop ins.
You need three parts: the standard latch, the threaded cap, and the lock bolt. Beware of the tiny plunger and spring in the rear end of the lock bolt when removing. You don't want to be hunting all over the floor if it launches when removed. You can remove/reinstall it with the gun in a 1 gallon size Zip Lock bag to be safe.
You can use the parts from any caliber I frame between 1948 and 1953 or even pre war I frame, before they began the flat latch ~ 1953 or any J frame after 1966 when the flat latch was discontinued.
There’s a couple styles used over the years.
I like the panache of the pre war ‘double pinch’ countour milled under top and bottom of the thumb pad:
My 30-1 J frame 32 S&W Long:
Photo by RKmesa
2nd style used, and first ‘new design' post war style thumb piece, still has the double 'pinch' but without relief cuts under checkered pad. Same as made for the Classic Series much more recently:
The 3rd style used (2nd new post war style) was a single 'pinch' in front of the screw hole like a #1 & 2 but from the center of the screw to the rear it's like the post 1966 regular style. Only seen on I frames: