[also posted in "Big Bore"]
I have a Model 70 lightweight sporter I'm thinking of rebarreling to 375 Taylor or 358 Norma. Other than opening boltface, what else will I need to do to get his thing to run?
Recoil lugs? Feed rail issues? Crossbolts even?

Thanks for any help!

You don't mention if this is a pre-64 or post. I'm assuming the caliber is 30/06 or 270.
If it is a pre-64 some minor rail work would likely be required. Post-64, hard to say. The feed rails on the post 64 rifles are formed by the mag box and receiver while in the pre-64 they are entirely within the receiver. Both are pretty neat cartridges. Regards, Bill.

On a Post 64 Classic, most actions for '06 size cartridges have a magazine box with the upper lips bent in. Either straighten the lips or replace with a box that is straight. Some of the belted case boxes have the lips bent also, and I have found that the feeding is much improved with straight lips. Some ramp work usually is required (open the ramp to a wide U shape) for the larger bore cartridges. Might have to open the rails up a bit on the front for good feeding. And if you remove the rear spacer in the magazine box, other things are needed, like machining the rear bridge for good ejection, a shorter ejector and bolt stop and the rear of the magazine opening in the receiver needs some work to allow room for the belted case rim.

Search the archives, there are a couple of posts last year with photos on lengthening a M70 for 375 H&H size cartridges.