Tough one. Most of the guys who used to put the gauge package together as a kit have stopped due to little demand. I just saw a youtube video recently where a guy installed a nicely gauged dash from another g-body in a Buick. It looked like a lot of work, but he showed it in great detail.
I just searched with google and found this:
http://worldofmotorworks.com/store/index.php?cPath=26
and this
http://www.superchevy.com/how-to/040...-dash-install/
I don't know anything about them, just the first things that came up when I searched. I bought my AVC kit from Dennis Kirban for around $600 when I bought my 87 from him in the early 90s. AVC is long gone, but I wouldn't recommend them anyway [mismatched gauge series cause uneven illumination on mine]. I remember here on the digest that guys did a LOT of work to make the AVC kit perfect, including sending the individual gauges back to the manufacturer to have the glasses removed, etc..
There have been great kits over the years, but nothing cheap, that's for sure...
Good luck.
Mike