Laser engraved is a good choice. Hand engraving will not look like factory stamps unless the engraver agrees to match the stamping.
Yeah removing the original caliber rollmark is another issue. Especially if it's on the lefy side of the barrel with the SMITH AND WESSON rollmark. If it's on the right side of barrel, sand it off leaving the barrel round. Apply your marking of choice, then have the barrel hot tank blued.
And don't forget the Dingbats* at the beginning of the factory caliber rollmark. Laser engraving makes it very easy to produce these and make your new caliber marking look factory.
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*i.e., Typographical Ornaments. Many wonder what the little iron cross-like marks are at the beginning and end of the cartridge and/or patent date roll mark on the barrel. Typographical ornamentation of many types was used as "feet", in printer vernacular, back in the day to begin and end text to help align printing, or rollmarks on barrels. The use by S&W, of their ornament choices we're so familiar with, began in the 19th century and used thru and after WW II on many models. They come and go throughout S&W revolver production over 100 years without any discernible pattern and is very inconsistent.