Altering the pre64M70 Hornet for larger .22CF ammo was not unusual. The early conversions, starting in the 1930s, were for the .22-3000 Lovell and its sharper shouldered version, the .22R2 Lovell. Griffin & Howe did these and altered the magazines as well. After WWII when the .222 Remington came out this became the favored alteration .... Winchester would not make the 70 for a Remington designed cartridge (altho there were a few 70s in .35 Remington) and it was left up to the gunsmiths. Lyle (I think that was his first name) did the K job on many cartridges, the Hornet was the best known, and while his work on a 70 spoils it for the collector it improves it for the varmint hunter.
