Do you have a factory shop manual with a wiring diagram? I am not sure about the Corvette but the ESC in trucks the first years could be jumpered to disable the spark control (I believe that it was a retard function). Your wiring diagram should show that the distributor functions independently of everything except the knock sensor........unplugging the spark control wont work.

In 1981, this stuff was pretty crude so they didnt have everything integrated together.