'94 HUD issue

Just picked up my 'new' '94 Cutlass Supreme convertible, flew to San Diego and drove her back to Colorado Springs. Have a few small issues; coolant level sensor, temp sensor for the gauge, gauge works but reads very low, will also be checking the thermostat, steering wheel controls for the heater do not work.
The HUD is getting power from the dimmer/power switch (can see the HUD panel lighting up), but no numbers/indicators. Is there a harnesss for the HUD behind the cluster, or are all the wires spliced individually into the system? What is the best way to get the dash apart to have access to the wiring?

A previous owner replaced the factory stereo with an aftermarket CD player. I'm wondering if they jacked up a bunch of wiring installing it. Anyone have an original AM/FM/CD they want to part with??

Thanks much!
Jeff