Nice! Looks like some variation of an Apollo 1240, with its battery removed. Those guys went through about a million different design iterations. Check it out here:
http://amiga.resource.cx/exp/apollo1260Hard to make out the oscillator from your photo but I'd guess you have a 33MHz model.
Also that link appears to show how to attach a fan, just connect it to the points shown in the photo. Note that you may be unable to close your trapdoor slot if the fan is on the bottom, but plenty of folks leave that open, or lift the entire system up on larger feet (for better airflow, etc.). Good find!
