OK - as this is a made in mexico coil - I cannot understand the resistor part, is it missing the internal resistor or does not require an external resistor.
Whip out your multimeter and measure the primary circuit resistance, if it has 2 to 4 ohms - then its a built in resistor and if it is 1.0 or something low then it requires a resistor on the positive side live to drop current to 9V (1.5 or 1.6 ohms resistor required) and a live wire from the starter solenoid point 50 to give it full juice on cranking, you may get away without this last bit or may need to add a relay or something to prevent backfeed to the starter - unlikely that the solenoid would pull in at 9 or lower volts but there is a possibility
If it is low impedance with no external resistance on the positive side you will be burning out contact points every now and then.