What brand of spark plugs have you had luck with

73 340 Elct. Ign. - Champion - never a problem.
71 340 Dual Point -Champion plugs would lead foul, glazed the porcelain until it would miss in a few hundred miles. Switched to Autolite and they worked fine.
I did experiment up and down in the heat ranges with both the high and low comp. motors with the Champion plugs, not with Autolite