Are there any plug experts out there? I've been looking, and coming up short, literally. I am currently running Autolite 3922s which are spoda be equivalent to NGK BCP7ES or AC FR1LS (superceded). I want to go 1 step colder per my engine builder's recommendation, but can't seem to find the right one. I ordered some NGK BP710s (Scummit substitution for BP8S), but I need the extended tip (haha) for aluminum heads. What ya got? Thanks!