Well a bit of an update...
Got a MP08 coil and wires from a goldwing, new plugs one heart range hotter than stock, and she ran (not very well) on both cylinders, only at full coke. So an improvement, but not great.
Then today I fire it up for grandpa to listen to, and he listens for two seconds, grabs a screwdriver, gives the sync screw a turn and boom, she idles great. He even turned the coke off, and she still ran. Why didn't I ask his help sooner!? Dad has said that for years he'd work on something for hours and Grandpa would walk over and boom, it would work. Now Grandpa's still doing it to me. There's something special about that.
But it still won't revv, just peters out if you try to slowly open it up. So I guess I'll try a carb rebuild kit, because it seems like it's not getting fuel. Like I've said before, I cleaned the carbs really good, but maybe there's still something off.