Black a smaller plug gap for higher compression.
The higher density of the air/fule mix needs more KV for spark firing time or a smaller plug gap.
A CDI has more KV power.
With Points I gap my plugs at .024" for 8 to 1 compression.
.022" for 9 to 1 compression.
.020" for 10 to 1 compression.
.018" for 11 to 1 compression.
.016" for 12 to 1 compression.
A plug gap of .024" for 8 to 1 will have the same mas of air/fuel in the plug gap as a plug gap of .016" with a 12 to 1 compression will have.