You don't need to mess with the temperature range on the plug. Just get the factory replacement Autolites. They are cheap, and they are good quality. I've always used Accel 300+ wires. They are a great wire, and you can order them through Advance. They have like a one year warranty on them, and I would just go in once a year and tell them they were bad and get brand new wires every year. There are all kinds of opinions on ignition wires, and there are a lot of good ones out there. Just stay away from Motorsport, Moroso, and MSD wires. Those are the ones that are known to suck.
Kurt