What you NEED to do IS tailor the spark curve.
For now, remove the heavy spring in the points distributor and only run the one lighter spring, this will get maybe 18-20* initial at idle being that the running of only one spring will have it partially advanced, this better for vacuum/setting-or ability to lower the blades more throttle response etc...
or if you have a welder, weld the advance slots, set it to the highest initial timing it will start with 'fully warmed up' and what ever total/full advance it likes limit by welding the slots.
with a light spring kit=$4 from mr gasket, it should be full advance by like 22-2400rpm w/2 light springs or 1200rpm with only one light spring.
it should be lumpy with 245*@.050 + slant 6.jmo
you should be around 3/4 turn out on each idle screw.