The standard rifling pitch...
and groove diameters of the two calibers are the same - it should work out fine.
Be aware, however, that the standard Weatherby chamber has a long freebore ahead of the chamber, which is necessary to keep pressures within spec. with factory ammo. If you intend to use factory .257 Wby ammunition in the rifle, be sure to chamber to factory standards.
PRD1 - mhb - Mike
Later:
I've built several custom .257 Wby - chambered rifles on Ruger #1 actions, with 10" pitch barrels I made. Most of them had short chamber throats for handloaded ammunition and were marked 'Not For Factory Ctg.". All of them shot very well.