Haven't seen one of those for a while.
First, I assume the plugs and points and timing are ok.
1. there is a vacuum controlled mixture unit, or maybe a tear in the hose going to it. It usually mounts on the fender with about a 3/4 inch hose going to it.
2. another common problem is oil on the trigger points in the bottom of the distributer (not to be confused with the ignition points)