Shoulder Belts In A 68 Barracuda Convertible HOW and WHERE?

In my 64 Valiant convertible I plan to install front seats from a Mustang Cobra convertible. They have the shoulder loop at the top of the seat, so you can ground the belt on the floor. In my 65 Dart, I am installing front seats from a Sebring, with integral shoulder belt. A lot of modders like those. Both have a powered driver's seat.