1973 Dart Swinger cooling

The direct drive 7-blade fan is more than adequate.The only fan-clutch to use is a thermostatic type which accomplishes the same thing but may reduce power consumption at hiway speeds....... if it goes into slip-mode.
IMO, If your engine is healthy and the ignition timing is adequate, then all you might need is a shroud, and the fan should be half way into it.
I have run lots of 318 cars without shrouds, but our summer temps up here are rarely past the high 80s, and then not for more than perhaps 3/4 days in a row. Today tho, it hit 90, now we're having a thunder shower, and things are cooling off nicely.
For comparison; I use an ancient 73 318 A/C rad, to cool my 400hp plus, 11/1, 367 cuber and it works just fine. And no, I didn't cut the core support to fit it.Yes on the shroud, the 7-blader and T-clutch. I run a 207* minimum coolant temp and I'm sure the aluminum heads are pretty good radiators.