This is how you limit or lock out the advance on a HEI distributor
Adding a simple dash mounted toggle switch to interrupt the spark power for hot cranking, allows you to start a hot motor with locked timing
Its just that easy.
It will idle clean, respond to the throttle and GLH when you rug it.
And it will likely be a whole whole lot better on gas (if you can keep your foot out of it)
When you get the distributor mechanical curve fixed up (or simply locked out) the vacuum advance hose goes to the ported vaccum source on the carb.
Be sure th PCV system is working. its part of the carb design and essential for correct idle.