That distributor brings in the timing FAST and LOW.
Disconnect and plug the vacuum advance. Use a NON-ADVANCE timing light preferably or use yours with no advance dialed into it. Use another light to confirm yours works properly as I've first hand seen one that doesn't. Mark your harmonic balancer at 34 degrees with a sharpie or paint pen. Shoot the light at it and rev to 3000 and make the line you made line up with zero on the pointer. Lock the dizzy down. Now check initial timing. Rev to 3500 to check total at 34 degrees again.
Let us know where the initial falls.
Then, with the vacuum advance still UNHOOKED AND PLUGGED, go drive it. Let us know how that goes. Your issues IMO are 100% timing related.