Check the coil resistances, using the FSM or Haynes, or this link as a guide:
http://www.geocities.com/berserko_1/c50/
If you have nothing coming out of the coil, and the resistances are good, then maybe the part triggering the coil is bad, ie the transistor, which is integral to the unit if you go to buy a replacement. Lots of spare to be had at the wreckers, or even from members (myself included), but rule out the basics of the unit. I had an ECU fry the spark drivers? and it would do nothing to spark with every other unit replaced in the chain.
<- avoid taking that route and poke around some more.
