67 Dart cooling issues
Let me preface my reply / opinion by stating that I despise electric fans when they're used in-place of an engine-driven arrangement .
Here's my recommendation for what it's worth :
1.) 5-7 paddle viscous fan in the O.E.M. style (make certain to use a fan clutch . direct-drive fans are garbage , as are flex fans ) ;
2.) 185 - 195 degree t-stat ("fail safe" t-stats are available as well ) ;
3.) 16 lb. radiator cap ;
4.) Fan Shroud ;
5.) Distilled Water , mixed 50/50 with coolant ( do not use tap water unless the water where you reside is "soft" or filtred ) .
I've had good luck with Water Wetter (et al.) . It fills-in hot spots in the cooling passages ; definitely needed in a hot climate !
Distributor vacuum advance needs to be plumbed to the carb , typically at the Throttle Body's base .
A wider radiator is better than a thicker (more rows) radiator . A 26" rad will fit in your Dart's core support .
Good luck :glasses7: