You want the grain in a stock blant to run from as far back in the butt as possable and run in a gentlycurve up through the grip and into the forearm. This blank shows just about perfect grain, I have followed the grain with a china marker to help show what I am talking about.

When looking at a blank from the top or bottom you do not want the grain running at an angle off the sides as this too can cause a blank to be weak and also increases the chances for warping. A good stock bloan will be air dried for at least 5 tears, ten is better. Kiln drying is not good for blanks as I am told that it can make the wood brittle though I do not know this first hand as I have never used any kiln dried blank.
Generally you can look at a blank and tell if it will work out. On rare occasions you may find a suprise after you start shaping the stock. I have found internal checks when cutting a blank down to the pattern size. The person who I bought the blank from replaced it pluss shipping. I also have found a few small bark pockets but luckly they cut out.
If any of you people would like me to look at a blank feel free to send some pictures and I will give you my opinion of the blank. As to what other woods work out well for the big kickers Rock Maple, Origon Myrtle and that is about all I can recomend from first hand experiance. The African Black thorn, like I used on my double holds promice but I will reserve judgement untill I have shot the rifle a lot more.