Jim, do you know how that tank vents?
Seems odd that it'd run well down the road if the vent was bad, but also seems odd that an early car like that would not have a vented cap.
As far as the advance, it won't do anything to fix your problem, and honestly, the 3/8 line may not either. I'd be 100% sure you are vented first, pump second, line third, and not touch the distributor unless you need to.
Also make sure your air cleaner lid isn't too close to the choke horn.