Which Sparkplugs for GT40P's?

[Shotgun28]

What spark plugs do I need for my GT40 P heads with and without Nitrous. I am more concerned about without at this point, until spring. I prefer Autolites, just trying to figure out what size. Thank you.

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91 LX Convertible Gray on Red B&M Shift improver kit,ASP red alum. underdrive pulleys, Richmond 3.73 gears, 1 5/8 Flowtech long tube Headers and off road h-pipe, Flowmaster 2-chamber cat-back with S.S exhaust, MSD 6A Ignition with coil,Cap and rotor, Taylor Pro wires, K&N 12" conical filter system, Jet stage 2 performance chip and just purchased some GT40P heads, looking at exhaust, Lentech Street Terminator plus on it's way...