plug recommendations?

"There are two issues with Champions. Number one is guys running a different brand of plug and using a cross reference to pick a Champion. That's a bad idea. Cross reference charts are essentially a guessing game at best. Look in the catalog and pick the plug for your application. If you are looking for a racing plug, get on the phone with someone who knows the plug line."

Ain't that the truth. I chose Autolite's for my newly rebuilt 273. My Champions converted to a colder heat range than I needed. I already went from 10.5/1 to 9.6/1 which should use a little warmer plug. I fought a rough/rich idle for a long time until I screwed in a set of warmer Champions and all was well.