16 gauge wire should be plenty to carry ignition primary current, no need for the heavy stuff. Find a source of direct battery voltage like the big cable terminal at the starter, or the Battery terminal at the voltage regulator, and run a jumper wire from there to the coil terminal that DOES NOT connect to the distrtibutor. On a Chevy it will be the (+) terminal. With the jumper in place, the coil should produce a spark when the engine is cranked, regardless of the position of the ignition switch. Don't leave the jumper connected with the engine stopped and the points closed- - - -it will burn the points in a short time.
Jerry