Alan, when you cut out your old floor boards, usually the 2 "cupped" sections (or is there 3?) along the outer perimeter of the floors, where the body bolts hold the body onto the frame, are in good shaped. I would advise cutting around these areas and leave the cupped portion intact, along with the body bolts. This will insure that you don't disturb the integrity of the body on the frame. And do only one side at a time, to further keep your body rigidity intact. You can cut your new Heritage floor board to match the cupped area, again leaving about an inch of overlap; you may have to use a body hammer or ball peen hammer to bang the new metal down to fit against the old. Then weld away! I MIGed with spot welds about every inch, used Cleco rivets to temporarily hold the panels together. When you "connect the dots" with your welder, jump around so as not to create too much heat in one area. Remember, there are some critical tubings under the driver's side, like fuel and brake lines. Check to see if you need to remove these first. Also, I think it would be smart to take your fuel tank out, don't want an explosion.