12v Switched near Radiator

All,

I'm wrapping up my dart project and am wiring in the fan relay. It is going in under the battery tray. Question is, in my 73 Dart is there a Switched 12v source for my relay at the front of the car? Not main power 30 in but for terminal 85 coil. Trying to avoid as much back and forth wiring as possible. Maybe a/c old lead for the A/C? I'm using a one wire alternator if that matters into the equation. I have a manual but I did not pick up on a choice.

Thanks,
Marion