First off, welcome. Now as to your stock, if this is your first gun of this type, you have nothing to worry about. The grain direction won't matter much in the forestock. The barrel holds the stock, and does a great job. These guns don't have the recoil, and shock of those suppository modern guns. While the wrist grain is somewhat important, most kit makers are pretty good at positioning the blank in the carver to get the best you can expect. I have broke one wrist many years ago, but it was an extreme drop of over twenty feet down a ravine in the dead of winter. If your still wary send it back to Jim, and he'll make you happy, but I don't think he would have had it in a kit if there was any doubt on his part.
Bill