Its very simple to do, yet very time consuming. Mounting the guages doesn't take much time, its the wiring and circuit board construction for the trouble lights thats alot of work.
My guage face does not have the trouble lights in the same location as the OEM faces, mine run across the top of the face all in a row. I like it better that way, its easier to make and all the icons are up high in your line of sight, not hidden by the steering wheel.
All my guages are Fiero. I did that so that everything wires up the same without any guesswork of compatability. If you're building on a Fiero with a Fiero engine, it only makes sense to use what was designed for the car.
I have the dot matrix in the upper center of the guage face. There are many ways to make this work, but if you go with a "off the shelf" display, you will need the circuitry to drive it as well. I made my own display with micro size L.E.D's, and then came up with a driver board using diodes.
The complete working guage face (without the dot matrix display)would cost about $650 if I were to build it, as long as you supplied the guages. It takes about 30 hours to build.