I still "tune" with champions. They are cheap. I can go through them without too much worry and their heat ranges are accurate.
Once I settle on the range, I use a better plug. BF32's never were quite right but are what the original engineering specified often. The issue was probably never the plug but a weak ignition system?
If you look at the current application charts, those have been replaced by BF42's which are still available.
NGK's I find to be a very high quality plug. It's heat ranges seem to be very accurate.
In the case of my 67 GT500, I never expected the original plug to be a BF42. Huh?
