Douglas Barrels makes Ruger barrels, threaded contoured and chambered. To fit the Ruger #1. Final fitting has to be done by
a gun smith including the ejector recess and the 1/4 rib.
A 30-06 Ruger #1 could be rebored and the chamber exept the neck could be left as is. If you are going with the odd ball 35 Whelen then by all means have it done in Ackley improved for best case life and best head space retention. The 35 Whelen AI
is a fine performer and much better suited for hand loading, me thinks.