I dont know the years but have a friend who did a lot of extractions of bad Ford plugs for people. I would anti seize and torque them. Spark plugs do last a long time now days but the problem is sometimes it's too long and better to break them loose and service them. It's like any other fastener over time but this fastener can get very costly. I always cringe at hearing people say stuff like oh dont worry about any stuff that falls in the hole it will go out the exhaust. Duhh.
Blow any dirt away from the hole, loosen the plug a few turns and blow the crud away again. Compressed dirt around the plug can cause the plug to not transfer heat properly and run too hot. Yes Kroil is excellent stuff. If you did start to back the plug out and it's difficult, as a skilled machinist you already know that you want to soak it and work it back and forth, not force it.