You will need to use the denser/harder of the two blanks as the .404. If both blanks are soft then it would probably not be a good idea to make a hard recoiling rifle stock on a soft piece of wood. But it's your choice of course. If they are both hard and dense then it is going to come down to grain flow. If you are going to send it to a competent stock maker he will tell you which blank for which rifle. And it won't be based on which one is prettiest.