Hi @[deleted],
Not sure if original resistor will suffice but you will require some sort of resistor kit when fitting Spal fans, (Evocarlos, Milo and a few others have fitted them, so they should be able to advise).
For info, Part #: 90589723 Resistor, radiator fan (bosch 3134503069) (used with air conditioning) (used with manual transmission)