1974 Dart Swinger

Pull a plug, connect a wire to it, place it on a ground (exhaust manifold) crank and see if there's spark at the plug. If not, start with the ballast resistor on the fire wall, many times they, or the control module, fail and you're just DIW (dead in the water).

As for the timing, if it was running fine before then that's a good place to start - check the manual and set at the recommended advance/retard then tweak to your desire.

I'm betting it's the ballast resistor or the control module.