Battery cables
As I recall, BATT- cable (black) went to the top of the RV2 compressor on my 69 Dart slant, or maybe it was the other end of the brace rod on the head. On my 1964 Valiant slant, it went to one of the block mounting bolts for the power steering pump (I don't have). Best to find a manual with photos since most cars would have changed that cable by now.
I think the BATT+ cable in all early A's (slant or 273) should go to the big stud on the starter relay. The wiring diagram shows that. From there, another red cable (always hot) continues down to the starter, along with the solenoid actuation cable (brn I recall).