I got a digital dash out of an 87 GTA, was wondering what is involved in making it work in my 89 GTA?

I want to if that counts, lol. I'm thinking about making my own though since I'm good with electronics. I'm just still not sure where to find some of the kits so that I can. I'm still looking for information on the ECM, such as what voltages and pulses go to the guages and what the ECM does with the raw signals. Basically I need a "Theory of Operation" for everything to do with the instrumentation.

Do you or anyone else know where I can get this information?