Wow...............technically incorrect.
'...they say the wire (singular) from the coils go to the "points" and to the battery.'
Wire(S), or TWO. One wire from battery + to coil + and other wire from coil - to points. And then twinned on the point lead for the other coil. The battery/coil lead can be singular. If you use one wire to do both battery and points you get a direct short that sets the bike on fire. Not trying to be an ass although I do that quite well, it's just that if one does not know what points are then there can easily be other gaps in VERY basic knowledge there as well. The battery + thing is wrong too, it should be off the ignition switch or the battery powers the coils all the time since there is no mention of a kill switch either. Ergo, battery runs down and burns points up at the same time.
The entire premise of the OP is way too simplistic in layout to be making a harness there.