The motorcraft plugs are good. The main problem with your statment is that you would use them on any engine, no matter how heavily modified. That is bad juju. For example, if you have a supercharger, use nitrous, or even a turbo...you are going to want to run different plugs. First, you can't (well, not recommended too...) gap an iriduim plug (came standard on PI cars....maybe NPI cars, but know mine was an iridium). You also need a different heat range plug for different things. I know that in my build, I am going 2 heat ranges cooler NGK BR7EFs.
There are just way too many variables to say the stock plug works for everything.