There are a couple of people that have done custom gauges for their ride. It's really just a matter of deciding what you want and doing it. A custom wire harness is a must for just about anything you do if you you use aftermarket gauges, not difficult if you plan it all out and take your time doing the work.
In my case I just used a piece of cardboard cut to the correct size. I then cut out the circles for the guages. I tried several different layouts before I got the one I liked best. As you notice my guages are not symmetrically placed because there wasn't enough room to get all 6 guages (tach, speedo, fuel level, coolant temp, oil pressure and voltmeter) in a symmetrical pattern that looked good to me and I decided that the assymetrical arrangement that I finally choose looked best. After making sure that the final cardboard template was correct I transferred the pattern to aluminum sheet (about 14-12 guage is ok). The plate was epoxied to the instrument panel although you could use screws (epoxying made it look cleaner). Actually the electrical wiring was more difficult. The stock wiring harness has a connection at the printed circuit for the instruments, this is where I put a plug for connection to the instrument wiring harness. You have to match the wiring, you need a factory wiring diagram. The turn signal lites are LEDs and the high lite and brake warning lites are stock with another custom wiring harness for connection. Use electrical guages for easier installation. You will need new sending units for the oil pressure and temp sending guages but you can reuse the fuel level sending unit (make sure the guage is for 0-90 and not the older 0-240 ohm unit). You can reuse the speedo cable after you modify the end for attachment to the speedo head (I reused the clip from the old speedo). Use a 3-3/8 speedo and tach and 2-1/8 for the other guages, larger guages would be more difficult to fit. I used Dolphin guages (on the internet) because I likes the look and they are cheaper than Auto Meter, VDO or Stewart Warner. I am very happy with these guages. Visibility, especially at nite is great. The only thing that I would change is to set back the panel into the pod for less reflection.
I'm sorry but I didn't save the old template but the're easy enough to make and then you can have your own unique instrument pad. The wiring will vary a little from year to year and also what the stock instrumention is. The plugs, wiring, LEDs can all be obtained at Radio Shack. Good luck and if I can help you furthur let me know.
For mine I used the orginal gauge blackout for a template. I traced the layout onto a piece of 1/8 aluminum and cut it out. I then cut out the top and side pieces to fill the gauge area. All the time I was using the gauge pod to make sure the sides and top would be filled it and it would look right. After I got the pieces right I held them in place in the pod and marked the 'open' area that I was going to be able to put gauges. After determining where I could put them where they would not hit I used a hole cutter to cut the gauge holes. After that I took everything to a fabrication shop for welding. While I held the pieces in place the guy tack the pieces. Then I removed them and he welded them the rest of the way. After that I had the piece polished and then anodized black. Then wiring and install. Kinda the Readers Digest version of about 3 or 4 weeks of work. Here's a picture of what it looked like after it was welded. There are a few more pictures at my site under the El Camino portion and then interior pictures.