Not trying to be picky, but correct. That distributor negative is not "ground", it is often black wire, but all black wires are not ground. The body of the distributor needs ground. Best to add ground wire from distributor screw to intake. When distributor clamp is loose for adjusting timing, ground can become intermittent, it can stress the HEI module. The distributor black wire does connect to coil negative, but no ground connection at that point.
