Jerk and stall when put into gear?

Ported vacuum -- the distributor vacuum advance should go to the carburetor's vacuum advance port, not to anywhere else unless this '66 is equipped with a distributor vacuum control valve, see here. Note this is not the same as an OSAC valve (mounted on the firewall in '73, on the air cleaner housing starting in '74), which should be bypassed if present, which it probably is not on this '66 unless someone has swapped in a later motor without de-equipping it to '66 levels.