The bracing for a convertible will go from the top of the right forward door jamb, to the bottom of the left forward door jamb, and from the top of the left forward door jamb, to the bottom of the right forward door jamb.... Same pattern for the rear door jambs. Then a couple brace running legthwise in the car between these x's. 1" X 1" 11ga. square tubing is adequate for the braces. Once the car is all straight and things are securely welded together, the cars will stay in place. The jambs are welded into the sill on the bottom....make sure these joints are not rusted out or the spot welds torn out. For a convertible, an extra gusset or two welded in at a 45 degree angle from the sill to the jamb will add a lot of stregth. Be sure the gussets on the rear door jambs to the sill do not interfere with the operation of the rear window mechanism....

PS--don't think you're the only one who has ever bought a basket case based on what in has the potential to be rather then just what it is you're taking home!!!!!