Tune up, 1960's style!

[shp4man]

Set the timing at 8 degrees before, that's 4 marks on the timing degree tab, or 1 mark under the "A" on the indicator with the vacuum advance unplugged.
I'm thinking the "A" stands for advance.
Check the operation of the vacuum advance and the centrifugal advance with the timing light.
Vacuum is way faster, but with the vac advance unplugged, timing should also advance about 20 degrees when revving the engine past about 3500 RPM. That's the centrifugal advance.
Makes a big power difference.