Have at it. No great decrease in value when you alter one of these factory original guns, but the increased comfort and eye appeal will be well worth the time.
First thing is to figure what you want and then draw out the form on a large paper. Compare to what you have and take rough measurements. Say you need a 3/8" off each side of the grip, convert to a POW grip, ect.... Then start at the head of the stock and work backwards. The weight reduction will be several ounces but teh comfort increase will be much greater. A fat club works but is not fun to carry or shoot.