Reconstructing (not "restoring") a former military rifle into its one-time appearance can be great fun, and a very instructive learning experience; these two aspects already are good reasons.
As long as one does not represent the final product to be something that it is not - a historical military rifle -, and as long as one observes the proper protocol to ensure this for posteriority, I would have no problems with it.
One hint for the work: be careful to check that the new stock has its metal recoil lug insert, and the two spacer pillars for the two stock screws. If the stock is blank, do not put a number on it.
As to prices, one can still find Carcani in moderate condition for about double the quoted price of the stock alone.