Stupid Distributor Questions

Man oh man george, your not having any luck are you?

Do me a favor, fire it up and while it's idling block the top of the carburetor with your hand and see if it dies.

Also if this is a factory 340 set the timing for 32* full advance @ 3400rpm.
Plug vac advance for now.

Have you had an exhaust leak lately by chance?

And have you compression tested all the cylinders and pulled valve covers to see if all the rockers are actuating the valves?

Tell me again when this all started happening and what you may have done [if so] before this happened.