Your timing is probably out of wack! You'll need to reset the timing:
You need to get #1 piston to TDC (top dead center) on the compression stroke. To find this, you'll need to take out the spark plug for #1 cylinder and have someone turn the motor while you put your finger in it. When it pushes your finger with air, you know you're on the compression stroke. Then, install the dizzy so that it (the rotor)is pointing to the "1" on the cap. Start the car and set the timing with a timing light.
If the car doesn't start when you get the #1 piston to TDC you probably have it 180* out(or you didn't get it on the compression stroke). So in this case, you'll need to get the rotor pointing back to the one, then pull the dizzy back out, rotate the motor a full turn, then reinstall the dizzy like I said above and this time she'll fire up!
As long as you didn't unplug any of your wires, this will work. If you mixed up your firing order, you'll need to get the firing order and make sure all your wires are going to the proper cylinders.