Clayt,
That shouldn't make any difference - the voltage to the coil is dropped by a resistor in a 12V system. Actual voltage across the points is only about 4.5v if I remember right.

Those wire looms do cause problems for some guys - mostly age deterioration of the wire's insulation from what I've heard.

Also a consideration is the firing order and how the wires touch each other. I've seen some crossfire trouble without the looms where 1/2 and 8/6 wires contact each other. firing order 15486372

On my '48 driver, I've even slipped plastic loom material between those wires that are prone to trouble. I don't like the look, but it sure saves headaches.