There were over 91,000 32 Safety, 1st Model revolvers made, from 1888 to 1902. With a 3 digit serial number, it would almost certainly been manufactured the first year, so non-medallion pearls would be appropriate.
As for value, I have to admit that $300 is quite steep for this model, even though condition is very good. There are many of these guns in near perfect condition, due to the facts that they were often purchased for a desk or bureau drawer, and overall a very weak cartridge that precluded many from using them as a carry gun. I picked up the example below a couple years ago for $110 with holster at a local gun show. Pearls may be original, but tons were installed by distributors and purchased by owners as well. They are selling for $100+/- on average, while hard rubber stocks are selling for $50, so only a $50 added value. There might be a pencil mark on the inside of the right stock indicating a serial number?? Can you measure the total thickness of the stocks? S&W stocks were substantially thicker than almost all non-factory examples. Those that I have measured indicate that many replacement stocks were a 1/4" or less thick at the base, while factory stocks average 3/8" thick. The complaints must have been heavy with the thin stocks, since S&W started placing sections in their catalogs and in gun boxes about the inferior quality of non-factory stocks.