The Ruger No1 is a fine, strong, platform for most of the old NE rounds, within reason! The largest you can go without modifying the action it's self, is 500NE! Though the 577NE has been done, it requires opening the action a good bit. Not only the safety, but the actual action body has to be opened up to a great extent, and leaves the chamber walls very thin, unless the threaded area is enlarged as well.

The reference to certain numbers not being suitable to re-bore , and rechamber to the 470NE, or 500NE from the 458 Win Mag No1H, is true, but like evryone else, I can't remember what the cutoff number is, but I think it is on the Bowen web-site! The safety can be altered enough to work in up to the 500NE (the same head size as the 470NE), by simply shortening the front slide area of the safety button.

I want to caution you about re-chambering the 45-70 No1 to any of the NE rounds. I have one that was rechambered to 458 RCBS, and it is about as much as I can stand to shoot in a rifle that weighs under 8 lbs. The 458 RCBS, simply being a lengthened 45-70 to a case length of 2.75" is a good one for this re-chambering, but if you go larger, I would start with the No1H .458 win mag. unless you re-barrel to a heavier barrel!

I for one would like to re-bore, and re-chamber a 30-06 to 9.3X74R, for a scoped rifle, to go with a little S/S double rifle I have in that chambering!