How old is the electronic ign harness? The wires coming out of the ballast are prone to cracking and breaking from the heat put out by the ballast. A new harness is probably the cheapest thing to replace,yet the most work.
When the resto was done a year ago I personally went out there and re wrapped the engine bay harness which was a mix of mostly new wire soldered into the proper connector's both new and old .Thats also when we converted the ignition from points to hei so it's basically a new harness tho it was made from scratch not bought . If the car hadn't fired right up yesterday and again this morning I would have bought the new parts and trusted them when the car fired but now I've got that darn paranoia going I'm going to trace what I can with out unwrapping the harness and check the grounds etc....but I think I'm going to change out some parts anyways ,the guy who did my resto has shown himself to be a liar and a thief so who knows how old the "new" parts he used really are , the coil and box could be thirty years old for all anybody knows and I never liked the plug wire set he put on so I'm thinking an upgrade across the board is in order maybe I'll call Hughes on Tuesday and see what they recommend for use with their 426 SB stroker which is what I'm looking at going too when the dollar gets a little higher and I can play the exchange and get the Bank of Canada to pay for most of it eh!