Good point on the lower side of the RPM/advance. It is idling more than 650 at the moment and you are probably right that the mechanical is likely adding few degrees.
I'll start with 12 initial and with 24-26 that will put me at 36-38 total.
I'll put the purple spring back in and see what happens. I need to run to summit today anyway, so I'll probably pick up the curve kit above just so I have it.
