72 Duster, 360, not firing or starting

Did you check for voltage at the coil? Is the rotor in there and turning with the cam?
No the engine will run just fine without the alternator. And I doubt the plugs are the issue.

On a different note,
Are you aware that by putting the throttle spring on like a chebby, you are putting extra stress on the throttle body, where the throttle shaft passes thru it? If you flip it around and run it to the front,then that spring will oppose the cable and wear will slow right down.
Are you aware that running all that rubber fuel line with gear clamps, and a plastic filter is risky-business?