No spark...

"Mopar original stuff"
This is a very fine system, generally trouble free.
In it's first iteration, this was a dual ballast system. The one side reduced the power to the ECU, and the other side reduced the power to the coil.
If either side fails, the sparks go away.
However, the power to the Dual-Ballast, takes a torturous path from the battery to get there. So you have to check every connection.
The circuit is from battery to the fusible link, to the Bulkhead connector to the amp-gauge, to the ignition switch, to past the #1 splice, and back under the hood thru that doggone Bulkhead connector again, then to the spade lugs on the resistor, out the resistors to the devices, and finally, the ECU gets grounded to the body, which ground then splits; part goes to the engine block, then out the negative cable back to the battery; and the other part goes to the body-ground cable and from there to the battery

Whereas the Coil gets it's ground, back at the ECU, thru the switching transistor, and from there thru the ECU case, and back to the body ground, lol.

By my count that is about 21 connections or more.
The only one you don't have to worry about is the #1 splice.
The thing is, from the #1 splice the blue wire splits off in at least three different directions. Coming from the Ignition switch it goes to feed the Dual ballast, and the electric choke, and the alternator.
And if your car has A/C I think it went to that system, and if a convertible top, it went there as well. But not to worry, that #1 splice is a welded brute that I have never seen make trouble.
However, if one of those circuits is sucking all the power, well then the coil gets what it gets. So I always keep that in mind.
However, the First and easiest place to go is to check the ECU ground path. That lil nugget has to have a nice clean and tight ground. Last time I checked, oh about 1999, lol, they were screwed onto the PAINTED firewall or apron with a special screw. Chances are after four or five decades, that factory screw is long gone, and has been substituted with whatever the PO found handy. So remove the ECU, clean the case and the mounting surfaces. Then find two STAR-loc-washers that are able to penetrate the paint and reattach the ECU good and tight. If a hole is stripped out STOP!
Either fix it, move the ECU, or use machine bolts and nuts. It's gotta be well grounded. The last thing you want is to be caught 1500 miles from home, with No spark, No tools, and in the rain, at night. You can fix it now or you can fix it later, or you can pay some country-bumpkin Chevy guy to tow it to his shop where he will tell you that your car needs 2 days of diagnostics which you then spend in a flea-bag Motel; to replace everything, cuz you know, what can you do about it.........
Yes I'm exaggerating, but you get the point.

You can prove your ground is no good just be jumpering the ECU case to anything nearby that you know is grounded, like the engine, or the alternator case, or you know...... the battery, lol.
I can tell you that maybe 9 times out of ten, yur gonna find spark rightaway, lol.

Good luck Mr. South Sweden.