If you just want add-on pusher fan(s), mostly for AC condenser and tranny cooler, I recently rigged a cheap-bastard system on my 1965 Dart (yellow car):
Dual Chinese 9" fans, $27 ebay, mounted w/ metal straps rather than the stupid push-thru nylon ties. They come as a puller, but I just reversed the 2 wires and flipped the flan blades over to them pushers. Probably not enough airflow to cool the engine, but helps the AC and trans coolers when going slow or sitting at long stoplights.
Controller is PN for my 1996 Plymouth Voyager, a solid-state relay which drives two much bigger factory puller fans, so "should work". They rivet it to the steel bumper, so my bolt to an aluminum plate w/ heat compound "should work". 4 wires - thick "BATT+", thick "Fan Out", thin 12 V "IGN", thin "short to gnd to actuate". Recall $25. Bought since could use it on my minivan otherwise.
Sensors are all temp switches which short to ground to actuate. One is PN for my 1985 M-B which screws onto its refrigerant filter-driver, just solid copper no penetration into the refrigerant needed. I tapped a blind hole in a plug (recall 6 mmD) to mount it. Another is in the radiator, TS145 for GM (if reading my notes correct). BTW, that radiator is for a 1972 Dart slant, though mine is a 273 (I know, bad choice at Autozone long ago). A 3rd temp sensor is at the outlet of the transmission cooler, a Derale PN I recall.
In my 1965 Newport and 1964 Valiant (red car shown), I used a factory pusher fan for my 1985 M-B. Most are similar into the 1990's. They have a rigid aluminum frame and their tubular mounts can be leveraged, plus I used the little horns on the mount in my Valiant. In M-B, only the refrigerant temp switch above turns on the fan (via 30A Bosch relay). The controller is a Hayden 3651, I got cheap new from a liquidator. It can only use its hard-wired temperature sensor, which I placed at the radiator top. It has a pot to adjust turn-on temperature. The relay is standard replaceable 30A Bosch. The extra blue wire is for a 2nd fan. Downside is you can't turn on the fan with refrigerant temperature, unless you wire a parallel relay for that.
Some designs turn on the pusher fans whenever the AC clutch engages, but seems an unneeded waste at highway speeds. My Newport has a Holley Commander 950 which can actuate the fan at a set coolant temperature, so I might later rip out the Hayden controller. I also have two fan relay harnesses I got cheap on ebay ($15 ea). They were made to dealer-retrofit a GM cross-over with additional fan for Phoenix (factory recall). Turned out too clumsy to use, but suitable anywhere a relay is needed. They have a fusible link.