the way he's welding the bag mount on the frame he wouldn't have to do anything but drill holes in the lower bars and move the bag mount in on the frame.
also, the two link setup is the only setup that can allow you to have an offset bag mount with reasonable bushing life. once you place bushings on both ends of the link bar, you're bushings will destroy themselves every time you're not laid out. your bushings, bags, and link tabs are going to have so much more added stress on them this way.
I highly recommend centering the bags.