You need to leave the extractor in cylinder while reaming as the 22 mag case is slightly larger diameter and the reamer will cut the extractor a bit.

The cylinder may or may not fit. Some yoke tubes are slightly longer or shorter, so your new cylinder may need shims or the center hole cut a bit deeper. Or you could trim the yoke tube and then add shims to the orgianal 22 lr cylinder. As some said you may have to adjust the ratchet teeth a bit.

The cylinder is way more than strong enough for 22 mags. I and others have made a K22 cylinders into a 327 mag cylinders with no problems. I have also made one into a 22TCM cylinder and another into a 22Harvey Kay Chuck, both of which are way more than any 22 mag

Also the cylinder and barrel don't care about the fact that the 22 mag is slightly larger. Once it hits to forcing cone it instantly becomes bore diameter. Guys regularly shoot 223 dia bullets in 22 Jets and some even use .224 bullets. It is a total non issue.Guys with large throat 45 colts regularly shoot ,454 bullets down ,452 bores. 44 mag guys shoot .430 bullets down .429 bores.