Tony,
You are correct, that is the date of manfacture BUU Jan 1949. These models were manfactured from 1939-1962 approx 375,00 made. Value, my best advise is to go to GunBroker and tipe in Remington 511P there should be some there and give you an idea of what they are asking for them. The P is for peep sight, these will bring more than a regular 511, you should find some clips there also. Ruger has a website you can look up the manfacture date on your Ruger, you father-inlaw is a good guy, two nice guns.
Joe