I'm running a 1966? Chev. 327 W/ I believe mid seventies unleaded heads,
mild cam and a Mallory Unilite electronic distributor and Mallory coil. I want to make sure I am using the right sparkplug. At the moment I'm using Autolite AP 145. I'm not sure if I should match plugs w/ engine year or year of heads? The engine is installed in a 2600# Model A Coupe. Thanks for any imput.