I have a "pusher" fan on my 68 Dart. It is a Mr. Gasket 18" I believe. I updated my radiator with a "Champion" aluminum 4 (I think) row. Stock opening in the rad. support. 180 thermostat. Water only with water wetter. 440, 12.5 - 1 pistons. It runs 170 - 190 for me. I usually don't sit in traffic. Alot of the time, I don't even turn the fan on as I'm driving. If I do get in traffic or sitting idling, I flip the switch on and don't worry about it.

Wire it up correctly and you do not have to worry about the original wiring handling the draw of a fan. Use a relay and a hot wire (fused) directly from the battery with a switch or a powered wire from the original harness to the relay activator and you are good to go. The relay activator only draws like 3 amps if I remember correctly. It may be even less.