If you have to ask.... It might be best to seek professional help. The torsion bars mount in a "reaction Plate" that bolts in. If the car has rust damage in this area it is probably not safe to drive, and it needs to be fixed properly. Getting the reaction plate mountings wrong will nake alignments and so on basically impossible. If, on the other hand, you are just planning to replace the dropped sections of the floors (a common repair) then proceed ahead.I have written before about how the entire skin of an etype is structural It is important to do it well. Measure measure measure!.Obtain new panels before cutting anything out You can use the new parts to make cardboard templates to guide you on where to cut.