Sorry I got the voice mail too late for me to come by before you had to leave. If you in fact do not have spark after grounding the plug to a GOOD bare metal ground try this:
Hook a jumper wire from battery positive post to the + side of the coil. you will get a small spark. That's OK. Now start the car. You have just "hot wired" the engine. If it starts your problem is ignition switch, or wiring going from the switch to the starter solenoid. If it doesn't start I would suspect the coil, condenser or you may have fryed the points because you hooked up the battery backwards in your previous tests. After you're done with this test you are going to have to disconnect the jumper to stop the engine. Don't run it with the jumper too long or you will burn up the points.
I'll be back home on 12/29 so if you like you can give me a call on my home phone, the 540 number I gave you when we spoke and maybe we can walk through some other tests. You've eliminated a bunch of things that it's NOT. Believe me when it finally starts it'll feel good because you'll know YOU fixed it. Good luck.