Chris,
The system chart for the FSQ-85ED reveals that it uses the same CAA as the FS-102 -
http://www.astrovid.com/documents/FS...al%20SysTX.pdf
Based on this information, the business end (focuser end) is 2.7", not 4". We suspected that anyway, but this confirms it. So you'll need to do some trickery to get the Takometer to work with a 2.7" CAA. Its just bracket that you'd need to make.
Again, if your not heading the robotic operation path, I don't think its worth your worry. Its like when you motorise your focuser with a Robofocus unit...using it manually i.e. for visual use becomes a pain as its slow to step/move the draw tube. Such devices are really meant for imaging purposes. If your instrument is only used for imaging then its worth it. I've never had an eyepeice attached to the business end of the FSQ. I hear they are a nice visual instrument as well, but I wouldn't know. For as long as I can recall, there has always been a camera there - even when polar aligning or syncing the telescope pointing model, I do it through the camera.