Welcome to the forum. The numbers on the concealed frame surface are temporary assembly numbers and don't mean anything after the gun gets the final serial numbers applied. The absence of a Model designation on that surface indicates production before 1958. These guns were introduced in 1948, so that establishes a 10-year window. To date the gun further we need the serial number from the butt. It will have a K prefix.
Your gun has been tricked out as a target model, with a wide target hammer and what appears to be a King rib sight. The hammer could be a factory option; the ventilated rib sight is not something the factory put on the gun. The stirrup attached to the frame permits mounting a Hogue rubber grip in place of the original diamond magnas or diamond target stocks that probably came on the gun when it shipped.
Value is probably in the $500-550 range. I am knocking off dollars for the lack of original stocks and adding a bit for the upgraded rib. Not everyone one will be in the market for a modified revolver, but some of us like those guns that have been upgraded from the company configuration.