Is it possible to run the XFree86 X server on a powermac 7300 if one
adds a video card to one of the PCI slots?

  http://www.netbsd.org/Ports/macppc/x11.html

suggests that this is not possible, but I am looking for confirmation.
Here is the relevent excerpt:

  Which models can run XFree86? (top)

  Only models that have supported video cards with appropriate Open
  Firmware initialization. In general, this means only recent models
  (i.e. Open Firmware 3) or a supported video card (such as an ATI
  Rage 128).

-russ