checked your earlier posts. With a 236-242 cam you are not quite up there to requireing locked out timing for best idleing etc.
But you do need a good bit of base initial idle timing.
I suggest you rework the distributor advance curve as follows.
26deg initial at idle,,,, 36deg at full mechanical advance. (2800-3000rpm)
That means you want a limited 10deg mechanical advance curve.
The mechanical advance can be limited to 10deg by various methods.
(search my old posts)
Then.... 10-- 12deg of vacuum advance max limited by a vac advance stop plate. The vac adv rate will need to be found by trial and error drive testing.
(use ported or full man vac as a source your choice , try both use what works best overall)
Then... when starting, employ 15deg-20deg of start retard for easy hot starting.
With this setup you probabily won't need the interupt switch to aid starting 99% of the time. But is real handy for the 1% when things get hot.