It will fit fine, normal grafting procedures to make the two join together. Trying to remember, without looking at the books, if the torsion bars attached to the subframe on the Cordoba, or if they attach independently like the B bodies earlier, part of the unit body construciton. I know the Cordoba has body rubber mounting points but can't remember the ends of the torsion bars. If part of the subframe, easy grafting to existing frame, if part of the unitbody construction, tie their location into the frame so one full box piece ties both torsion bars together for strength, don't weld or bolt to the sides of the frame, notch and box for driveline/transmission tailshaft clearance, but keep it one whole unit, much stronger that way, .125 walled 2X3 would give good support for the torsion bar end. As far as the width goes, youi say the 'doba is four inches too wide, right? Offset tires will fix that on the front side. If that doesn't feel right, section the center of the K member three inches, readjust engine mounts at the K member, you have enough room inside the engine bay to do that, and although it sounds like a bunch of work, it really isn't, and moving the motor mounts outward won't be difficult, some of the Cordobas had big blocks in there, so that should ease the fear of the upper control arms interfering with the engine itself.