make the mech advacne curve 10deg.
This will allow 26deg inital at idle and 36deg at max mech advance.
The timing must not drop off in gear.
Vac advance is a separate thing. Use ported advance. Should add 10-12deg max at hi vac cruise.
The increased 26deg base inital advance at idle will clean up the "rich idle" and allow you to readjust the pri and sec throttle position.
12 deg at idle is not near enough for a cam like that. You can make the curve limit 10deg
or simply lock out the emch advance and set the locked fixed timing to 34-36deg.
Set the idle with a manifold vacuum gauge.