JB, if you have a 180 stat, i would find it hard to believe you actually run 130 sustained. the stat really regulates the temps - if below 180, the stat closes, so it does not matter how good the radiator is. do you have a real gauge, and where is the sender for it?
zeus, try to find the ISO circuit. on 87+ stangs, there is a dedicated fuse for it. not sure on your 86. also, there might be one wire for the dimmer circuit on the back of the headlight switch. pull the switch and put the probe of a test light on each wire (ground other lead). then turn on lights and as you probe each wire, move the dimmer (you have a dimmer, right? i dont know). when you find the wire that allows the test light to dim when the dimmer is turned, you have the right one. use this to power your gauge lights.
alternatively, if no dimmer, just find the parking light feed (under dash - look at schematics - on my 88 it is a brown wire), or use one of the wires on the back of the switch that is hot only when the parking lights (and headlights) are on. use it and your gauge lights will come on with the other lighting.
i think autometer sells different color bulbs, or covers for the bulbs. im not sure on that.
good luck.