Which box are you using to replace the factory spark box? I'm using the stock Duraspark system in my 77 Comet, but so far, I'm not at all satisfied with it, compared to the Pertronix II and Crane XR-1 I've used in my 89 Ranger. I did pick up some better results with a wire swap ( to Ford Racing 9mm's) and a Blaster 3 coil. Haven't run it enough to tell if that's going to clear up the missfire it was getting though. It did sound somewhat better though. Hopefully I'll get the oil pan leaks fixed enough this weekend to allow some street running to burn off some of the carbon on the plugs.
Wasn't two minutes after I pulled into a freind's driveway that he came cruisin by.
Still got an oil drip from the front radius of the pan though. And the rear suspension is "squirrally" I think maybe my pushing the leafs toward each other wasn't a good thing to do when I swapped rears. I'm going to loosen the U bolts later and push em outward and see what that does.