Gazelle Champion Mondial AA single speed conversion project

3-leading/3-trailing would have worked if you'd laced it right. Would still have been as ugly as sin, but that's a aesthetic problem not a mechanical one. All the spokes which are permanently deformed (and that's all of them, as you say) are scrap. In general, the only place where outbound spokes should be interlaced with inbound spokes is at the crossings furthest from the hub, which means just 3 pairs each side on your pattern.

I was following this tutorial and did exactly what it says there:
http://www.baldurdash.org/OtherStuff/3leading3trailing.html