The case is the same to start. Rechambering wont do you any good, you cant put a 35 slug down a 30 barrel. You can have the existing barrel rebored to 35, and rechambered to 35. There are several good shops that do that. If it were me, I would just buy a 35 Whelen barrel and have it installed. In all honesty, I would just keep the 06 and find a 35 Whelen to buy. They are on the market quite regularly, its the Whelen carbines that are VERY hard to find.