Is the vacuum advance working?

A simple test is to remove the vac advance hose while the engine is idling.
If the idle speed goes down that's an indication the vac advance is working.
Although, you should shoot the timing with a light to assure that it's working correctly.

Along those lines, when you timed the engine, was the vac advance line disconnected?
It should be otherwise you're giving away a lot of horsepower and it could be retarded enough that it overheats.