1977 XLCH Ironhead Sportster spark plugs

[renn.ses]

Any suggestions on which brand spark plug tip type and item number to use on a 1977 XLCH Ironhead Sportster that's been bored and stoked to 1200cc with:

Dyna electronic ignition and coils
S&S Shorty E carburetor and breather
Custom made 2 into 1 exhaust with Supertrapp megaphone muffler

Any info will be greatly appreciated,
renn.ses@live.com

[Dave63]

Regular Autolite plugs. No special anything.