Just having the chambers reamed out to the correct 32 H&R length. Any gunsmith that has a correct reamer can do this and/or you could purchase a reamer and do it yourself. A reamer would probably cost in the $75 - $90 range, I do not know what a gunsmith would charge you. The best ballistics from a .32 long is around a max of 850 - 900 FPS with 90-100 gr bullet, the 32 H&R can be loaded up to around 1200 FPS with the Hornady 100 gr XTP. I think Factory H&R is around 1100 FPS.
It does need to be the "J" Frame version, any "I" frame will not have a cylinder long enough for the 32 H&R.

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H Richard
SWCA1967 SWHF244