I've rebuilt both the top & bottom ends of my HP500's with mild components. Dart Iron Heads (308cc Intk vol.) & Intakes, crane 731 CAM all new valves, lifters, pistons, etc & CMI E-tops headers, all new Crane Ignition, coils, etc. We're staying with the stock carb and rejetting back to stock. Not exactly sure of the HP they're going to produce, but we're estimating to be around 530-560. Knowing this, what spark plug suggestions are out there?

I run NGK v-power 5674-9 on a similar 600HP motor, if your heads are taper seat spark plugs, this should be a good choice.

.033 to .035 gap.

Should the spark plug choice be run by Dart? Since it's their heads?