Setting back a pre '64 Win 70 barrel will not cause a stock bedding problem. If it's got the fore end screw to the lug under the rear sight, just remove it then relieve the stock for the barrel swell to clear. Free float the barrel and one's good to go.
Rechambering any barrel to gain a few thousandths headspace typically requires the old chamber to be completely cleaned out. That might require the barrel to be set back as the reamer's profile probably won't match the chamber's profile to start with and steps and ridges will be made where diameters are different. Replacing this one's bolt may only need its face to be squared up and set back a few thousandths if the headspace is too short.
And yes, the barrel tenon may need to be recut if the barrel's set back. Clocking in the barrel's easy if one puts witness marks on it and the receiver face before starting.
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
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Last edited by Bart B.; February 7, 2013 at 11:16 AM.