I bought my '69 Chevelle about 2 1/2 years ago. Due to the time elapsed and having changed out a fouling carburetor, I want to put in a new set of plugs and then run them for three or four thousand miles to get a good reading. I'll adjust the temperature from there. What's a good baseline plug to start with? My specs are below:

'84 GMC 454 (461)
Stock compression
Stock heads (peanut port)
Isky 270 cam (.510, 216/216, 114)
High-rise intake
Edelbrock 1806 650 cfm AVS
Recurved GM HEI
Headers with 3" dual exhaust
TH-400 with 1800 stall
2.73 open 12-bolt

Also, I'm presently running 8.5mm MSD wires which have about 10,000 miles on them. Is it necessary to change those wires out if they look decent?

Thanks for any advice.