In the meantime, here is an excerpt from the article...the suggested wiring diagram for adding an Electric Cooling Fan:
Figure 6. Circuit for retrofitting an Electric Cooling Fan. Temp sensor activates Fan Control Relay, which supplies ECF with (Battery, not Ignition) Power. Optional Manual Switch and Indicator are shown added. Chassis Conn. Relay only allows manually activating ECF during engine (Ignition) ON, so prevents a dead Bat if driver were to forget to turn OFF Manual Switch after parking, but automatic control would remain functional. Fusing the Battery Power supplying this circuit, is good practice. For Fuse value, measure Steady State Motor current and double that value for the Fuse. (Reference: Fusing Rules.) Two ratings of Snubbing diodes are shown, A type for low Relay coil current, B type for High Load current.or B type could be used in all three circuit locations.