A few thoughts:
Put the rotary tool in the closet before you start on the stock. If you can't do it without a rotary tool, you can't do it.
It takes five years to cure a gunstock blank.
Think twice about a first time job without refinishing the metal.
Using the original stock as a pattern will probably screw it up.
The last, best way to screw up a gunstock is checkering.
You get what you pay for.
It's all about the quality you expect in the finished product.
Best of luck.