The challenge is today's typical auto parts supplier (Autozone and Pep Boys, to name a few) is manned by people that can take instructions and type well ("Year and model of your car, sir?") but wouldn't know a spark plug from a spark arrestor. I think a cross-reference could be easily built. Whenever I need a gasket for my Windsor-based build, I typically start with 1970 Mustang or Torino (something that offered a Windsor in it back in the day) and then go from there.
But having a NAPA part # equivalent would be a REALLY GOOD thing to have.
I still have fun with the green horns when I ask them about muffler bearings and blinker fluid. Someone has to break them in.
-Dean