Car won't start

The wires he's referring to will be thicker than all the other wires. I'm not sure on the 67, but in the 66, they have ring terminals that attach to the back of the Amp gauge.

Unless you disconnected the battery, they are live wires all the time. If you remove the instrument panel and touch them to ground, you'll blow the fusible link (a normal looking wire with a "fuse" built in. It will have a molded "tag" on it. I replaced my fusible link with a 50 Amp fuse in a waterproof holder.