Ah, that's a ballast resitor so I assume it has points on it then. The coil won't work without it (it'll burn out). The 3.9 will be fully electronic and a 12volt coil, that can be swapped with ther old coil and resestor (resistor styas with coil). If it's electronic on the older car too then you should be ok with the newer coil.
the capacitor is just a supressor, radio interference, that can be fitted to either car.