I started the 70 yesterday and it ran about 30 seconds and just quit. It has no power at all to the car. I have a terminal block that runs electric fan, water pump and ignition which still has power. The terminal block comes directly from the starter, so I know I have power at least that far. I checked the back of the alternator and I have 13v there as well.

I started checking for voltage at other places and have nothing anywhere. I checked the horn relay, and the fuse panel and they are dead. I also bypassed the neutral safety switch in hopes that it may have caused it but no luck there either.

Does anyone have a schematic/wiring diagram as to where the power stops or starts so I can start tracing wires?

Sounds like the fusible link might have burned.
It's the wire that connects the positive battery cable pigtail to the terminal on the core support.

oops sorry Dean, mine has the battery in the trunk. If that link is still there, I don't think it is connected. I have 2 1/0 welding cables coming from the trunk to the starter, one + and one ground. now.

I don't have a diagram for a Chevelle with the battery in the trunk but the terminal on the core support should still be fed by a fuse link from somewhere.
Maybe it comes from the starter's battery cable terminal.

Time to get out the volt meter and follow the circuit back to it's source.

I am just trying to figure out where to start. I guess the horn relay maybe a good place, head back towards the splice, and then maybe I'll find the link.

I found it, it was a corroded wire coming from the battery, Dean you had the right wire, just in a different location on my car. Thanks for your help.