<VV> Cutting thru painted sheetmetal?

[Rick Loving]

My 66 Monza was converted over to turbo power many years ago by one of
the PO's.  At the time the exhaust cutout was not done, the exhaust pipe
was bent to stick out below the body at an angle.
 
I would like to cut out the exhaust cutout shape in the lower panel for
when I replace the exhaust, what can I use that will only require
dressing up the cyt edge with touchup paint and not repainting the whole
area around the cutout.
 
I need to keep heat to a minimum, obviously, but what should I use?
 
Rick Loving