First off you will need to strip off the old finish. This is best done with a Chemical striper.
Here is a link to a post of striping the stock.
http://www.surplusrifleforum.com/viewto ... 37&t=61170
After stripping the stock, you will need to steam out the dents. I wouls stram the whole stock to prep it for a light sanding.
Once the stock has been striped and steamed you will need to let it dry.
Once it is dry you will need to address the crack. Drill a hole into the crack with a small bit. You will need to drill at an angle from inside the stud hole. Use an epoxy (clear with 30 min. set time) to fill the hole. Be sure to put paste wax on the stud screw and screw in into the stock while the epoxy is setting up. After anout an hour or so remove the stud and alloe the epoxy to finish curing.
Use masking tape to cover the checkering. Don't make this hard on yourself. Just place long, over laping strips of tape over the checkering and then use a razor knife to trace the outer lines and remove the extra tape.
Using a sanding block, sand the stock lightly, starting with 200 grit paper then 300 then 400. Remember, you are only lightly sanding.
If there are some blimishes from where the old finish had chipped off, you can stain the stock just a little darker to blend them. But first you will need to deside which finish you wish to use.