I had no spark going to my plugs either. I started replacing from the other end though, I ended up replacing:
Coil, dist cap and I cleaned the button, wires, new plugs, and HEI. It works now, but I practically replaced the whole ignition system. I cleaned the wires going to the coil, and I followed them along the branch of the harness to make sure it was ok.
On mine, the coil was bad, but it had burnt out to 'look' like it had the proper Ohms. So it fooled us.