[68 P.O.S.]

Which carb are you running? If it has transition slots in the throttle bores, you need to pull the carb and set the slots to square. Then reinstall and setup your vac advance to provide no more than 10-15 degrees of advance. Honestly, you're best off with a Crane adjustable vac advance. Connect the vac advance to manifold vac, not ported/timed. Why? Because lean mixtures take longer to burn and need the extra advance. The lean mixtures are at idle and cruise. Connected to ported/timed vaccum, it has the opposite effect....no added advance at idle where it's needed, and increased timing during acceleration where it's not needed.

For timing, 10 isn't bad, but I'd bump it up to 12-14 degrees. Don't forget to unplug the vac advance when you set timing.