I just did this today, but used a welder. I cut a piece, folded up the outboard side (this was on my 72 truck passenger side) and then figured out where the bend in the floor was going to come in. I then marked that line, cut a V notch in the flange for the passenger kick panel, and then welded the whole mess in. I took a few pictures of the repair so email me KENZ if you'd like to see them. Its really not all that difficult and probably harder on the 72 as the floor has a 'crown' and dips down as it moves outboard.
