I used to own a 69 Chevelle SS automatic. I'm also an ASE Master Tech so here goes.
If it starts with your "bump" switch, then there is no power at the little wire on the solenoid. Check the purple wire under the dash at the ignition switch. The switch is on the top of the column under the dash. Not up by the key. There is a little rod that connects them. If no power at the purple wire then check other big wire (? red) going into the switch. If it is ok then probably the switch is bad.
If no power at the red wire then check the neutral safety switch. Located on the side of the transmission.
On cars this old you sometimes have to check the starter wire at all connectors.
Good luck!
John
