here's a video showing what the car is doing
Details on the engine
answers to some of your questions, I haven't tried all of your suggestions yet, but quite a few
In this video I lean it out and try taking the timing right down to 5 degrees at about 600 rpm and even if I take the timing all the way up to 30 I still get the unburned fuel.
FYI I do want to switch plugs to eliminate that variable but they are a couple days away unless I try NGK 2238