What could a bad regulator potenially destroy?

My 73 won't start (crank but not start), I'm not getting any spark while it's cranking. I checked out the ignition unit, ballast resistor, and the voltage regulator. I bought all three new and compared the measurements. The regulator was bad and so was the ignition unit. I replaced them and the ballast resistor, but the car still won't start (no spark). I checked the resistance on the reluctor in the distributor and it measured 300 ohms which I think is OK. The only other thing I can think of is the coil went bad, but I thought they usually acted up when they got warm. The ammeter isn't in the circuit anymore because I bypassed it. So as of right now I'm out of ideas. If it isn't the coil, what else is left?

Thanks