In those days it was copper core for the wires. Resistor were only added if a radio was mounted.
You may or may not have a radio in the Milleotto but you will certainly have GSM and GPS. So will the people around you.
Also, in the 80's regulations for interference became much more strict. This was not only for cars but for all electronic equipment incuding video monitors. The way the anode voltage for the picture tube is created is similar to the ignition in your Milleotto. At the time I owned a company designing and manufacturing video monitors. We became very critical about high dV/dt and high dI/dt or in other words sharp edges. Reducing the sharp edges and eliminating spikes did not only reduce interference, it also improved picture quality quite a bit and multiplied life time of parts.
Same can be applied to your ignition. Take away the spikes and very sharp edges and transform a short high spark to a lower and longer spark to increase efficiency of the spark in its role as starter of a combustion process of a fuel / air mixture and multiply lifetime of plugs and contacts. Any interference is also loss of energy.
The trick is to convert interference to useful energy by lengthening the spark. This is best done by inductance rather than resistance. Thus a wire wound core of the cable.
Resistors with relatively low resistance are ok. If resistance becomes too high the resistors will take away energy.
I would use BPR7EIX spark plugs.
Leads with a core wound with stainless steel wire on a Kevlar carrier. It is that wire I use to make the cables on
http://www.viva-lancia.com/specials/ignition/index.htm
Is the grade 7 NGK plug correct? Lancia did never specify NGK plugs. The Champion N7Y does not 1 tot 1 translate to NGG B7 or BP7. I never use the conversion tables
I use the Produktfinder at
www.ngk.de. I have always found it to be correct.
I just finished work on a Flavia Vignale 1800. The carb, ignition and cables were in a bad condition. After complete overhaul of the carb and replacement of the vacuum device, new cables and new ignition the engine did still not run very well. After replacing the BP7ES plug with BR6ES and adjusting the gap the engine ran very well.