Sounds like you are on the right track. Yes pushing it towards the firewall retards it.
Any fuel dripping in the carb throats? Do the carb idle mix screws have any affect when turned all the way in?
If it starts OK when warm at 16-20 degrees initial, that's usually a pretty good range.
I wouldn't hook up the vac advance at all until you have the idle sorted out.
Real lean and real rich will have the same odor, don't get fooled by that thinking it's rich, could be the exact opposite.