[RICK LAKE]

cobra 53 Rico before you start playing with different heat ranges on plugs, I would want to know what the A/F ratios are. The valves are not 100% seated yet either. With new parts would run the motor a little rich for 500 miles before getting crazy.
Thing I have learned from spark plugs range changing. If you use antiseize on the threads of the plug they will knock the heat range down 1-2 ranges. Don't have a 100% proof on this but this is from Antiseize themselves a few years back at a national event.
Color reading the plugs is also alot harder if running a multi spark module that gives up to 30 degrees of spark during firing. This work only at lower rpms to the 3,000 range on MSD system. Can't answer for others. Hear that the ICE system is better than MSD. Makes more power.
I not tryed Livewires. They have a capasitor in the boot by the spark plug and this helps may great spark and the wires are not cheap either.
From the pictures, at this time and new parts, stay with the 6's for a little while. Breakin and then recheck. A/F meter is really needed. Rick L