It must be 50 years old or older to be elidgeable and in original unaltered condition. Its all in the rule book you got with you license or on the ATF website
I suggest you review it, the answers are ther to most simple questions
http://www.atf.gov/firearms/curios/2001index.htm
Just exactly what did he change on the stock? If its the original stock and he just reshaped it and nothing else is different on the rifle it "could" still be elidgeable. Bottom line is if he doesnt feel comfortable shipping it to a C&R he doest have to