Spark Plug Advice Needed

RRR,
I will tell you why you do IDLE TIMING first.....

You bolt on your carb, factory 12* of initial timing. You find the mixture screws are not adjusting the mixture; you are able to screw them all the way in...& engine still runs.
You remove the carb & find too much transfer slot is exposed, giving a very rich idle that cannot be adjusted. To reduce the amount of exposed T slot, you drill holes in the t/blades for bypass air. Problem solved.

Then when you are tinkering with ign timing, you notice the idle rpm increased 200 rpm. And the idle is smoother also. WTF!
You check with the timing light & find the engine is idling with 30*. Another WTF moment!! The idle rpm increased because the engine is making more HP from the extra timing.....which it always wanted.
So now if this carb is going to be dialled in to give the best idle & vacuum, best tip in response, the carb does not need any bypass air; you now have some holes in t/blades that need filling in....
That is why you dial in idle timing FIRST....