The current recommended replacement spark plug for your engine is the AC Delco 41-101 Iridium which is made by NGK for GM. Warrantied for 100K miles. Also, you can use the NGK TR55IX Iridium which are available anyplace. The Autolite double platinum APP606 also work like a champ.
IMO the best ignition wire to use are the AC Delco Premium Silicone 7mm wires.