I have converted an 8x57mm 1908 Mauser, a 7x57mm VZ24 Mauser, and a 91/30 7.62x54 Mosin Nagant to 7mmRemMag.

I lengthened the magazine, widened the feed lips, opened the bolt face, and changed the extractor. In the Mosin I designed an ejector over-ride button for removing unfired ammo out the short port.

But so far I have not done any action alterations to M70 Winchesters. It is not the same as sporterizing cheap old military surplus. The M70 actions cost money and are already what they are.

I did just get one of these M70 extractor relief cutters.
http://pacifictoolandgauge.com/slot...el-70-extractor-slot-cutter-carbide.html

There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. -Ernest Hemingway
The man who makes no mistakes does not usually make anything.-- Edward John Phelps