Was Unibody Strengthened for Convertibles?

If a convertible top with frame is lighter than a steel hardtop, it cant be by much. If the top is power actuated, 100# seems pretty optimistic.

Aside from the torque boxes, there was some additional body structure for the top well. The only additional strength this provided was needed for attaching the top frame. Factory convertibles were known to be "flexy" compared to hardtops. Subframe connectors would be a wise addition to a convertible.