I'm pretty sure it is hot because it is running down over the headers, or because it isn't getting any air from your fan. The plug wires carry very high voltage with very low power. This is a formula for not needing much of a conductor. If #8 is getting too much resistance that is usually caused by a poor connection at either end or a break in the line. That would cause poor ignition, not overheating of the whole wire. Pull the plug and a couple of oythers and compare them If #8 plug looks the same there is probably not much wrong with the wire. If there is a problem #8 plug will probably look darker than the others.
i was just on the phone with a bud , the plugs all look the same , will try swapping out the wire with another ,the plugs and header distent are the same on all 8 , i`m also going to wait till it gets dark out and see if the spark is jumping , the car ( 67 firebird ) does run nice though , no bog or hes , thanks for your help.