Radiator core support / frame

Car is a 73 Dart 340 Sport. Adding a Champion 26" radiator with the Contour electric fans. The radiator frame on the body, along the sides of the radiator, has a slight bend on each side. How it got there I don't know, but I want to straighten it out before mounting the new radiator. The bends are just above where the radiator frame attaches to the front frame rails. I can't see any welds from the frame rails to the radiator support, but I also cannot straighten the support sides with them connected to the frame. How does the radiator support frame attach to the frame rails? I'll have to cut them loose, straighten the supports, then weld them back to the frame. I'd like to know if they're already welded from the factory, or just pressed together somehow.