I am thinking you will need to find a machinist or really a custom gun maker to complete the work for you. Take him your old barreled action and the new barrel and have him match them up. Hope it will fit your stock when it is done. I know a guy here in North Idaho that could probably do it for you - he build guns from the ground up...

Here is his web site

http://www.twilightsystems.com/design.html