74 Duster (318) ignition not working, not getting spark

Thanks. Especially for adding the info about the seatbelt interlock.

I only have a couple suggestions. Mostly so you don't melt or burn things. But also so you figure out what is going on.
1. Secure the ignition switch and add a start button.
..Hanging them by a stiff bracket from the dash is probably the easiest way to do it.
2. Get rid of that wing nut on the starter relay stud. Put on a regular hex nut. Do it with the battery disconnected. That junction is direct from the battery. Accidently ground that post with the screw driver or anything else metal and as you've already had a glimpse of - the battery can become an arc welder.
3. Someone has already said there must be a ballast resistor and they are correct. Take an multi-meter and check for resistance between the two posts on the coil. Even if its still connected, it won't be sooner than later if running without the ballast resistor. (Looks like a recent ECU. If so then only the .5 ohm resistor is needed.)
4. You'll need some tools and supplies. Multi-meter, Wire stripper, an open barrel crimper, heat shrink tubing, some packard 56 and/or 58 terminals, and some open barrel splice connectors. For wire in the engine compartment see if there is marine supply in the area that sells wire by the foot. On this side of the country the big stores have many colors to choose from in the typical range of wire sizes.

ps. Clean the needles out of there. That plus oil and grease will get nice fire going if a wire overheats or there's a good spark show. But cleaning will also make it easier to work well and get good connections.