Most any competent smith could do the work. However, it would be costly and probably in the end not worth it. For all the work involved my local smith would be in the $500-$700 range depending on the barrel manufacturer and grade of barrel you chose. The 30-06 is a great round and factory ammo can be bought at any place that carries ammo. The 30-06 is so plentiful that you can buy factory ammo designed for varmints to the largest game North America has to offer. So my suggestion would be hands down to leave it as is. If you want or need a 338 Win. Mag. you can buy one for the price of doing the work to make your rifle into a 338.