If he wanted to he could build a nice rifle out of the parts, there are 1903 recievers for sale from time to time, usually for about 200 dollars.
He could put his parts on that, get a Smith to set the headspace and have a complete 1903 A3. But if the investment cast reciever is strong eneough, and safe eneough to shoot, You could put a stock on it and shoot and enjoy it. Thats the problem with my Remington 1903 A3 I worry about shooting it and wearing it out.