I looked on my ZO6 and cannot see anything on the winshield.
I went to the service manual for my car and found out this would be very simple. The "data" feed for the HUD is simple a Class 2 Serial Data feed. This is the same thing you monitor with your OBD2 connector under the dash. These all meet a standard so the data coming from them is consistent.
For example, I use a program called HP Tuners (
www.hptuners.com) to monitor and program both by ZO6 and my H2 and you just plug the same cable into the OBDII connector and there you have it.. output.
If you can find someone that will loan you or sell you a hud relatively cheap.. you should be able to hook it up off the bench with an OBDII cable (
www.scantool.net, $16) and check it for function before you even attempt to cut a hole for it.
These should help you get started.