I actually bought what was meant to be a beat up realist recently with this in mind. Unforunately it turned out, after a bit of disassembly and lubing/cleaning/reassembly, to be a realist in good working order, so I'm loathe to tear it apart now. Like you I was attracted to the notion of the built in RF, if only for reading off distance, as the mechanism inside the camera that moves the film plane would not have survived the conversion. However, looking at it, and doing a bit of disassembly during the course of the CLA, convinced me it would not be a good candidate for a pan conversion anyhow. As nosmok points out, the advance is a bit awkward, the mechanism that holds the advance wheel sticks down into the film area in the middle (not a problem for stereo, would be a problem in the pan case. You could probably move the attachment up into the top plate somehow.
Anyhow, I ended up gutting an old broken Yashica Electro and milling out the film gate. Waiting for an m65 mount & copal 0 plate from rafcamera and some other bits and pieces.