What's the deal with champion?

Just because one spark plug cross references to another, doesn't mean it is the same.
Go to an application guide for the proper plug, no matter the manufacture.
Now when it comes to a modified engine, its a trial & error deal, no matter the plug MFG.
You made reference to a "MOPAR" plug, well the "MOPAR" plug was made by Champion for ever.
Now, the OEM plug from Chrysler Corp is Champions. Champion's are also referenced in the owners manual.
I have ran Autolites with no concerns, but prefer Champions in all my rolling stock & Racecars, thats the Mopar guy in me.
I go a full season on the Champions in the race car & we race almost every weekend somewhere.
The bottom line is, when it comes to sparkplug choice, get the correct one for the application. No matter what brand it is!