Early A shoulder belts?

The other day my wife and I were driving the Barracuda around town. When we arrived home she told me she felt frightened without seat belts. So, it's time to install them but I feel lap belts aren't that great. Has anyone ever attempted to install shoulder belts in an early Barracuda?
If you arent worried about being stock- find set of Chrysler Sebring or 200 seats- shoulder harness is built into seat....