Short BB Spk Plug Clear Headers, I think.

Shorty plug 440 update. Went to Jensen nationals. It was pretty hot on the drive up thru the mountains, 85 - 95 degrees outside. Engine coolant temps were around 210. These mini plugs performed great! On the way back at night in cool weather we were pouring on the fuel pulling lots of 2nd gear acceleration rodding thru lots of curves and putting the car thru its paces. We let those 3.08 gears stroke it on out in the straights. The car has never run so great. Having the short plugs which keep the boots off the headers works like a champ!
With about 500 miles on the plugs we are seeing 0 issue on this mostly stock 74 440.

.