In March this year I purchased Pete Ganzel’s Rokkor 58mm A-mount conversion kit. Pete was extremely helpful in providing information on how to swap out the ring and properly adjust the lens so that it will focus perfectly and all the distance scale lines up correctly. The lens was amazing on the NEX with an adapter, and it is even more amazing on my a55 and a700. I highly recommend this conversion if you have a Rokkor 58mm f/1.2. Also, Pete makes this conversion for other mounts as well, including m42 which he recommends. It is also possible to get a chip to install in the lens mount so that it will be recognized by the camera for focus confirmation.
For more information on Pete’s conversion see here: Pete Ganzel’s Rokkor 58mm Page
And here is what it looks like on my a55: