rigbymauser - are the .450NE completely wrecked, or is the top rib just snapped/separated?
It would be a compete shame (in my opinion here) to change caliber if the barrels had to be completely redone.
Would it be possible the resleeve new barrels to existing 'lumps' in the original caliber etc, but get inserts to shoot say a modified sub-cartridge of .458" rather than down load such a large cartridge with say Trailboss & light for caliber projectiles?