Holley Carb/squirters+jets ?
I am not familiar with that champion plug but here is a link to it. What you have is a cold plug because that champion is a race plug. Click the link and scroll down until you find the champion number.
http://www.edelbrock.com/automotive/sparkplugs.html
In champion a 9 is cold and a 12 would be a stock plug. I would try aomething in between the 9 and 12 for the $12 it will cost and see what happens. If you are 10.1 comp or higher try a 9 and go a little lean on primary jets.