No way any "adjustment" of floor or quarter will allow them to fit...not without doing substantial damage to the panels anyway. The only way would be to try spreading the lower frame rail and upper quarter panel rail with a port-a-power or something and see which spot welds tear loose and which panels buckle. Next thing you know you've got 2 cocktail shakers properly installed and your decklid doesn't fit or close anymore...

It would be far smarter IMO to just elongate the upper holes in the cocktail shakers and be done with it. Or relocating the nuts on the upper quarter panel rail probably wouldn't be too difficult either. Or maybe you can bend/modify/replace the brackets on the shakers themselves.