A '68 with the short water pump the timing tab would have to be off to the drivers side (left). Also need to check the damper. There are two damper timing mark locations. One nearly in line with the keyway and one with the mark about 12 degrees from the keyway.
The damper with the TDC mark inline with the keyway takes the timing cover with the tab to the left (drivers side).
The damper with the TDC mark offset (noticeably) takes the timing cover with the tab directly above the damper.