I'm running a 72 LeMans with a very mild 400. I have a Summit house brand aluminum radiator with dual DeRale fans and a Painless PWM fan controller. The controller uses a coolant temp sensor, which I put in the intake coolant passage. I set the fans to come on at 195, the controller starts them sequentially and at 50% speed, and ramps them up as temperature goes up. I've never seen temps over maybe 205, and that was on a hot day while stepping on it. Typically 195 is the highest I'll see for normal driving, and fans turn off around 190 (I run a 180 thermostat so it doesn't fight with the controller, but on the highway in like 70 or below weather temp will ride the thermostat at 180).
Debated intially about going with the DeRale controller, but decided I liked a temp sensor in the coolant instead of the push in style. The DeRale controller starts the fans at 0% and ramps up with temperature, which I liked better than the Painless controller that starts at 50%. But the temp sensor is what made the decision for me, and after some teething problems and a replacement controller (the first one I got was faulty, they sent me a new one free of charge) I'm happy with how the system operates.
Mounting the radiator was interesting because it isn't an exact fit in the factory location, so I had to get creative. But it's worked well for three years now, so I'm happy. There other brands that sell aluminum radiators that are more of a direct fit, and/or come with mounting brackets to take away the creativity I had to use.