What is minimum electrical required to start my car?

Sooo frustrated!!!

Ok can anyone tell me the VERY VERY minimum that has to be connected to start a motor? I want to disconnect EVERYTHING else. Like if motor was sitting on an engine stand and wanted to try and start it. I want to try and eliminate everything I possibly can and go from that point forward.

The car is not getting fire.

1974 dart sport with later 70's 360 electronic ignition.
Was running before my nephew touched it, he had it for 6 months and "said" he couldn't get it started. When he took it from here - he drove it. It was running on a gas can bypassing the gas tank.

Any and all help is appreciated, Thanks in advance.