I'll echo the sentiments of some of the other guys here...you can open up the bolt face of your current action if you want...I wouldn't rebore and can't think of many companies that would rebore such a small difference in calibers. Rechamber to .270 Weatherby or rebarrel.
Another option though...you could probably go on Gunbroker and find a complete M700 in 7mm Rem Mag for less than the cost of all the smith work to change your current action over. It was one of the MOST common chamberings a few decades ago so there's a bunch of them out there. Not uncommon to see them for less than $400 (sometimes way less).
True rifle loonies don't rebuild...they add to the collection.
