What's the deal with champion?

I found Champs @ Napa a few weeks ago for my 273. Autolites didn't work well because they were a heat range colder than originals were (which were already 2 ranges too cold for my rebuild. Dan, are the NGK's close to Champion's heat range? What's the best way to tell if the heat range is correct? Bonzai run and read the plugs? tmm