you could cut it along the trans hump and fan it out a bit. lots of massaging with body hammers. for mine, i spliced it back an inch or two and about 2 inches between each cut, tack welded part of it, hammered more to get it to fit, then tacked the next splice, then repeat.
Nothing a pair of ball peen hammers cant fix. Realize that you are working on a 43 year old car that has been twisted and heated, cooled, beat, abused, everything done to it, its not going to line up perfect everywhere. I would simply do as one listed above and force them together and tack it, no harm done. In some instances i would drill a hole and use a screw to pull the metal together and then tack it and then weld the hole back up.
Nothing a pair of ball peen hammers cant fix.
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In some instances i would drill a hole and use a screw to pull the metal together and then tack it and then weld the hole back up.
Remember, this stuff is mild steel, it was placed flat into a set of dies and smashed into a complex floor shape. Smashing it 2% more probably won't be a challenge.