Hi Keoke,
Actual required voltage to fire a plug is pretty much a function of cylinder pressure & plug gap.
I suspect that the Pert with Sport coil will work perfectly well at smaller plug gaps in the small distributors. The actual required firing voltage is still moderate, the cylinder pressures are usually moderate.
OTOH, with high cylinder pressures and or wide plug gaps, required firing voltage goes up & cross firing in the small air gap caps becomes more likely. The wide rotor nose on the old Lucas doesn't help the problem. Lucas rotors are also noted for insulation breakdown from rotor to metal shaft if the plug gaps are made too wide. In fact, they frequently fail at standard plug gaps, but that is a whole 'nother story.
Note the large diameter caps & some internal shields used on late model distributors to avoid the problem. The ultimate at this time is a coil on each plug with no distributor cap or rotor. A mixed blessing. I have a V10 with 10 separate coils to worry about.
D