From personal experience, I'd wire the electronic ignition for a 4 pin ballast and 5 pin ECU. That wiring can be used with either style ECU if one has a breakdown.
As for the recommendations to get a service manual, definitely one for the van and not just for the wiring diagram. I'd also recommend one for say a 72 to 75 mopar of some sort so you can copy the ignition system.
Why the Ford alternator?
Do they even make a 5 pin ECU? I haven't seen one since the 70's
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here's a quick sketch, not so nice but should get the OP what he was after
feel free to correct any errors as I was in hurry
