I myself just bought a mosin nagant, it is a 1939 izhevsk m91/30. I can't speak much for which model is best or what markings to look out for as I am still learning a lot about them myself, but I can definitely say 7.62x54r.net is your go to place for everything mosin nagant. I picked mine out purely based off of which one had the smoothest action. At first I had some problems cycling rounds, but after a thorough re-cleaning of the chamber and some polishing to the bolt's moving parts it works great. You can also refinish the stock fairly easily and make it look very nice. After all of the work I did to mine it not only looks good (IMO), but it's a mighty fine shooter as well. Goes to show that with a little work, anyone can take an old beaten up surplus rifle and make it almost as nice as a modern day bolt action.
I don't always get to the range, but when I do, I prefer dosAK's.