For what your gonna pay to have a used Rem bolt fitted and butchered you would be much better off getting a bolt from Pacific Tool and Guage.
I got one for my 260 build , it was ordered to fit the action which was fully blue printed and the bolt race ways reamed to be uniform and true , came with a Sako extractor and a custom bolt handel tig welded to the bolt and the smith did a great job fluting the bolt also. I'm not 100% sure on the cost but I'm thinking its about $200. But think about it a factory bolt is gonna cost $125 minimum and the fitting and machining is gonna cost at least another $100 and you still have a factory bolt , might as well have a custom bolt fitted and have the benifits of the WAY better fit.
Oh my smith was Nathen Dagley , his web link is in the box below.